Browsing by Author "Getahun, Abebe (Professor)"
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Item Aspects of Reproductive Biology, Growth Performance and Survival of the African Catfish, Clarias Gariepinus (Burchell, 1822) in Captivity for Enhancing Aquaculture(Addis Ababa University, 2018-12-12) Yalew, Alayu; Getahun, Abebe (Professor)Being a potential species for the development of Ethiopian aquaculture, some aspects of the reproductive biology, larval rearing and growth performance of the African catfish, C. gariepinus had never been addressed. Hence this research aims to compare the performance of different size classes on their reproductive biology different z the artificial propagation, larval rearing and table size production of the African catfish, C. gariepinus in captivity. Different sizes of broodstock groups were injected with pituitary extract and compared for fecundity, number of fertilized eggs and the number of survived early larvae produced. The larvae were provided with zooplanktons multiplied in ponds at different feeding intervals to determine the best feeding frequency. The African catfish were cultured in extensive, semi intensive and intensive systems at different stocking densities and the best performing stocking rate was determined for each system. The income return of the different practices was compared and evaluated t identify the best practice for Ethiopia. The result indicated that fecundity of 500-600g weighed broodstocks was 51,800 eggs/kg bodyweight but only 47,000 eggs/kg was spawned from 1000-1200 g weighed broodstocks. The percentage survival of early larvae from small sized broodstocks and larger ones was 81% and 76%, respectively. The larvae fed on local zooplankton performed successfully and zooplankton multiplied in ponds replaced imported Artemia nauplii effectively. At feeding frequency of four times a day (every three hrs), larvae showed an average daily weight gain of 18.9 mg/day which was 19% more compared to those fed fewer times and less frequently. The percentage survival was 95% for the group fed four times a day and 75%, 93% and 87% for larvae fed twice, three times and five times a day, respectively. The most preferred stocking density in terms of weight gain and survival was 1fish/m2 for extensive, 5 fishes/m2 for semi-intensive and 90 iv fishes/m3 for intensive system. And the final harvest or yield was better in ponds or tanks at higher stocking density; 2fish/m2 for extensive, 10 fishes/m2 for semi-intensive and 100 fishes/m3. The average yield was 0.66kg/m2 for extensive pond culture, 4.77kg/m2 asemi-intensive pond culture and 53.4 kg/m3 in intensive culture during 8 months period. Hence, for a better productivity, fish should be stocked at a rate of 2 fishes/m2 in extensive and 10 fishes/m2 in semi-intensive pond culture and 100 fishes/m3 in intensive tank culture. Comparison of the different culture practices for economic benefit (considering fish sale), indicated that semi intensive culture system benefitted more with a profit index value of 13 compared to intensive culture with 9.28. In conclusion, African catfish female parent with 500g and more live weight can be used as a broodstock in a hatchery rearing. Feeding live zooplankton cultured in plankton ponds could be the most consistent technique for Ethiopia since importation of Artemia cyst is not sustainable. For the sake of alternative fisheries and to run profitable business, catfish farming in a semi intensive pond using feed formulated from local ingredients would be a solution.Item Diversity, Relative Abundance and Socio-economics of Fish and Fisheries in the Western Part of Lake Tana, Ethiopia(Addis Ababa University, 2020-11-15) Tegegne, Sewunet; Getahun, Abebe (Professor)The fishery resource in Lake Tana has significant socio-economic contribution through generating income, employment and used as a cheap protein source for local people. However, diversity, relative abundance and socio economics of fisheries in the western part of Lake Tana were not well studied. So the aim of this study was to investigate diversity, relative abundance and socio economic value of fisheries in the western part of Lake Tana. The study was conducted from December 2019 to August 2020. Data were generated from field sampling, fishermen catch observations, key informant interviews, focus group discussions and through questionnaires. At the sampling sites, physico-chemical parameters were measured using MPS. Fish weights were measured from the fishermen catch at the landing sites. Data were analyzed by (PAST), SPSS software and by various descriptive statistics. A total of 6118 fish specimens were collected at all sampling sites. Thirteen fish species were identified with species diversity value 1.6. The evenness value in the western part of Lake Tana was J=0.62. All the fish species were present in all sampling sites, except that L. gorgorensis was absent at the sites of Kunzila and Delgi. O. niloticus (46.24%) was the most abundant species in number and C. gariepinus (28.39%) was the second and L. gorgorensis (0.6%) the least abundant species. From the value of (% IRI), Oreochromis niloticus was the most important species during the dry season with value of 22.48 % and C. gariepinus was the most important species with the IRI value of 32.67% during the wet season. L. crassibarbis was the least important species with the IRI value of 0.23% during the dry season and L. gorgorensis was the least important species in the wet season with the IRI value of 0.31%. 18.16 % of variance was positively correlated with environmental variance with C. gariepinus, L. nedgia, L. truttiformis, L. tsanensis and O. niloticus. The total fish catch composition in the study area were O. niloticus (54.3%), C. gariepinus (23.4%) and Labeobarbus spp. (22.3%). The fishing activities in the study area were 87.8% fishing alone and 12.2% fishing in groups. The majority of fishermen were used monofilament gillnets (64%) and only 36% used multifilament gillnets. The fishermen who fished alone and those in groups had an average income of 1907.75 and 3210.42 ETB, respectively (P< 0.05). The average income who had owned modern and traditional boats were 3300.00 and 1907.75 ETB, respectively: (P<0.05). The current fishing trends in the study area and the fishery conditions were threatened. Therefore, appropriate management action should be taken especially to control monofilament fishing gears in order to sustain the fishery resources in Lake Tana.Item Effect of Water Quality, Common Carp (Cyprinus Carpio) Invasion, and Fishing Activities on the Population of Nile Tilapia (Oreochromis Niloticus) in Lake Hayq, Ethiopia(Addis Ababa University, 2020-06-05) Tessema, Assefa; Getahun, Abebe (Professor); Mengistou, Seyoum (Professor); Fetahi, Tadesse (PhD); Dejen, Eshete (PhD)Ethiopia is endowed with a number of lakes located across the country in different ecological regions. However, most lakes are found clustered in the Ethiopian Rift valley but there are also few lakes located in the Ethiopian highlands (>1800 m a.s.l.). Lake Hayq is one of the highland lakes located in the north central highlands of the country. The lake fishery provides economic and ecosystem services to the local community. However, since 2010, the fishery production of the lake in general and the population of Nile tilapia, in particular, have been reduced. In addition to this, the growth of Nile tilapia has been stunted. There is limited information on factors that might have contributed to the low population and stunted growth of Nile tilapia in Lake Hayq. Therefore, this study aimed at assessing possible internal and external factors that could have contributed to the decline of Nile tilapia fish growth and the fishery. To realize these objectives, I determined physicochemical water quality, plankton community structure, fish diversity, relative abundance and some biological aspects of common carp (Cyprinus carpio) and Nile tilapia (Oreochromis niloticus) and assessed the effect of fishing activities on O. niloticus between January and December, 2018 using standard methodology. Though significant difference (ANOVA, P< 0.05) was observed in Dissolved Oxygen (DO) and water temperature between dry and wet seasons, variability in most of the physicochemical parameters was low in Lake Hayq. The low variability in physicochemical parameters could be associated with less climatic variability (rainfall and water temperature) and higher depth of the lake. The depth profile data showed that the physicochemical parameters including DO and temperature variation were less between the surface and the deeper portion of the lake. Hence, the lake was not stratified during our sampling period. In this study, the reduction in the concentration of total phosphorus (TP) and Chlorophyll-a (Chl-a) and increment in Secchi disk depth (SD) was observed. Thus, the change in these parameters contributed for the change in the trophic state of the lake from eutrophic to mesotrophic state. A total of 44 phytoplankton taxa grouped under six divisions: Chlorophyta, Bacillariophyta, Cyanophyta, Euglenophyta, Dinophyta, and Cryptophyta were identified in Lake Hayq. Chlorophyta and Bacillariophyta were the major groups in terms of species composition. Peridinium (Dinophyta) was the most numerically abundant species in most of the sampling seasons and sites and formed blooms. Currently, a total of 28 zooplankton taxa were identified from Lake Hayq. The number of both phytoplankton and VI zooplankton taxa was higher in this study which could be associated with a higher number of sampling sites and two of them were from the shore of the lake which might have used as refuging and feeding sites. A total of 1980 fish specimens belonging to three species, Cyprinus carpio (1055), Oreochromis niloticus (892), and Clarias gariepinus (33) were collected. The dominant fish species in abundance were C. carpio (53.28 %), followed by O. niloticus (45.05 %). The length and weight relationships showed nearly isometric growth in both female and male C. carpio. Males (596) were more numerous than females (459) which showed a significant deviation from the 1:1 hypothetical sex ratio in C. carpio. The length at first sexual maturity (L50) of female and male C. carpio were 21.5 and 17.5 cm, respectively. The length and weight relationships in O. niloticus showed negative allometric growth in both female and males. Male O. niloticus were more numerous (553) than female (339) which was deviated from a hypothetical 1:1 sex ratio (Females: Males). The size at first sexual maturity (L50) of females and males O. niloticus were 12.8 and 12.9 cm, respectively. Both C. carpio and O. niloticus have similar peak breeding season between February and April. In Lake Hayq, diet overlap was observed at a smaller size (< 12 cm for O. niloticus and < 16 cm for C. carpio). Fishing activities in Lake Hayq were fully illegal, fishermen have been used monofilaments of mesh s sizes of 4- 6 cm (below the recommended mesh size, > 8 cm). In addition to this, the selective fishing pressure on O. niloticus was higher for Nile tilapia. The change in trophic state from eutrophic to mesotrophic (low food availability), presence of similar breeding season, diet overlap, and fishing pressure (overfishing) especially on O. niloticus might have contributed for stunted growth of O. niloticus in Lake Hayq. Therefore, monitoring the limnological variables, restocking O. niloticus fingerlings, and closing the lake at least for two consecutive years should be done to improve the fishery of Lake Hayq in general and O. niloticus in particular.Item Effects of Niger Cake Inclusion in Fish Feed as a Major Protein Source on Anion Dynamics in Nile Tilapia-Lettuce Aquaponics System(Addis Ababa University, 2018-05-04) Amare, Liyuwork; Getahun, Abebe (Professor); Tadesse, Abebe (PhD)The aquaponics systems culture different organisms that are dependent on nutrients generated from feed. Most of the time the major protein source of this system is fish meal. However, the availability of fish meal is very scarce and the cost is not affordable for developing countries. So, this study was carried out to examine Niger seed cake as replacement of fish meal and also to compare the anion dynamics of Niger seed cake with fish meal. The experiment was conducted in five treatments, each treatment in duplicate, with the proportion of Niger seed cake; 0% (Control), 12.5% (TA), 25% (TB), 37.5% (TC), 42.5% (TD). Also a hydroponic treatment (H) was included to examine performance of each treatment on anion dynamics. Samples of fish, lettuce and water were collected every week for about five weeks. Both phosphorus and nitrogen groups (ammonia, nitrite and nitrate) were analyzed by spectrophotometer. The result of the experiment had shown that as the Niger seed cake inclusion increased in the fish feed (43%), TD, the increment of anion in the system was observed, which was comparable with the control diet. However, it had low anion loading than the hydroponic solution. In the lettuce, as percentage of the alternative feed increased, the concentration of anion became higher and comparable with the control fish feed. In general, the result of the experiment had shown little difference with the fish meal. Therefore, higher percentage of alternative feed from plant sources such as Niger seed cake could be taken as supplementary source of feed.Item Evaluation of Growth Performance and Body Proximate Composition of Three Strains of Oreochromis Niloticus L., (1758) Under Greenhouse Condition(Addis Ababa University, 2018-02-04) Gebreanenia, Gebremedihin; Getahun, Abebe (Professor); Dagne, Adamneh (PhD)Growth performance and proximate body composition of fingerling Oreochromis niloticus strains from different lakes (Chamo, Babogaya and Hashengie) were compared in tank culture system under greenhouse condition between April and October, 2017. Fingerlings of average weight 4.4 g were stocked at stocking density of 20 fish/m3 in tanks (1.2 m3 each) in three treatments with four replicate each. The treatment groups were fed formulated feed with 30% crude protein at a rate of 5% body weight per day. Fish samples were taken monthly from each tank for body length and weight measurement. Nutrient content of fish fillet was chemically determined following standard methods of Association of Official Analytical Chemists at the end of the experiment. Growth performance parameters (final weight, daily weight gain and specific growth rate), feed conversion ratio, body proximate composition (except carbohydrate) and survival rate were not significantly different (p>0.05) among the strains tested. However, the wellbeing of the fish, expressed as Fulton’s condition factor was significantly higher (p<0.05) for the strain from Lake Hashengie compared with those from Lakes Chamo and Babogaya. Body proximate composition of the strains were well in the range reported for tilapia except for the lower crude fat content of strain from Lake Hashengie, which was reported to have the highest compared with O. niloticus strains from other lakes in the natural system. The reason for no variation in the growth performances of the three strains could be due to the culture system where culturing tanks were under greenhouse which brought the culture water temperature in the optimum range for O. niloticus growth. Despite the optimum culture water temperature, the daily growth rates of the three strains were low which might be due to breeding, and poor nutritional quality and low digestibility of feed. The feed quality also explains why strain from Lake Hashengie had lower crude fat content while has the highest crude fat in the natural system. Generally, based on the current finding, strains of O. niloticus either from lakes Chamo, Babogaya or Hashengie can be used for further experiment and stoking activities with feed supplementation. However, we strongly recommend further research to be conducted in this regard with standard fish feed and more strain included since this is the only study reported under greenhouse condition.Item Fish Biology and Fisheries of the Floodplain Rivers in the Alitash National Park, Northwestern Ethiopia(Addis Ababa University, 2019-05-03) Eyayu, Alamrew; Getahun, Abebe (Professor)Ethiopia is a landlocked country endowed with over 13637 km2 of standing water surface area and 8065 km river length arranged into 12 drainage basins and harbor unevenly diversified fish species of which about 20% are endemic. However, there is lack of a trust worthy quantitative ichthyofaunal accounts of these basins. Among the notable ones in the country, the Blue Nile and Tekeze-Atbara Basins span the northwestern parts of the country and are fed by many floodplain tributaries originating from the Ethiopian highlands. Except that of the Lake Tana sub-basin, the middle and lower reaches of the floodplains of the two basins generally lack an inclusive study on ichthyofaunal diversity, ecology, biology and fisheries. This study was thus undertaken to fill these gaps in some floodplain rivers in the Alitash National Park (ALNP) for management options. Fishes were sampled using gillnets (mono- and multi-filament) of different mesh sizes, cast nets, electro-fishing, traps and mosquito nets from six sampling sites of the three “temporary” rivers (Gelegu, Ayima and Shinfa Rivers) for two dry and two wet months (April 2015 to November 2016). Physico-chemical parameters were analyzed to examine habitat preferences of fishes. A static bioassay toxicity test was done to test the piscicidal efficacy of Balanites aegyptiaca on a pond experiment. A focus group discussion and structured interview were also employed to assess the fishing activities and socio-economic returns of the small scale fisheries in the ALNP area. Different statistical tools and methods were used to compute both biological and environmental data. From the total of 2719 specimens, 43 fish species with some new records of the two basins, included into 25 genera, 15 families and 6 orders were identified. A total of 11 species are new records of the present study. The Cyprinidae which constituted 10 species was the dominant family followed by Mormyridae, Alestidae and Mochokidae represented by 6, 5 and 4 species, respectively. Gelegu River was species rich and abundant. Based on frequency of individual occurrence (%FOi) in all assemblages, only 5 species fell in the category of “euconstant occurrence” or their FOi was >75%, while many species were laid in the “constants range of occurrence” (FOi=50.1-75%). About 77.5% of the total importance of relative index (IRI) was contributed by 12 species. In Ayima, Gelegu and Shinfa Rivers 16, 12 and 17 species had a significant contribution in relative abundance and accounted for 84.7, 85.9 and 95.3% of the total IRI, respectively. Among the group of physico-chemical and environmental variables; EC, site depth, secchi depth and river channel diameter were the key environmental factors determining fish community structure. Similarity percentage (SIMPER) produced an overall average Bray-Curtis dissimilarity of 60.8% between the fish communities of the three rivers and about 51.2% of this global average dissimilarity is accounted by 17 dominant fish species. As a result of fish species abundance and environmental variables association, the redundancy analysis (RDA) showed that eigenvalues of the first axis (λCC1 = 69.0%) and second axis (λCC2 = 24.0%), where CCA2 and CCA4 axes accounted for 79.7% and 96.5%, respectively of the species environmental relation. The final model accounted for 77.2% of the total variance in fish composition and all canonical axes were significant (Monte Carlo test 499, p = 0.002). Length-weight relationship, condition factor (CF) and feeding habits of five selected commercially important fish species with a total sample of 449 from the Ayima and Gelegu Rivers have been identified and examined. All species had a growth pattern of negative allometry to isometric and positive allometry, while only Labeobarbus bynni had a CF value greater than 1.0. All fish species consumed a large variety of prey, however only fish, macrophytes and detritus were the most important contributors to the dietary variation in predator fishes. Although, all fish species were a generalist feeder, some fishes also seemed to be specialist feeders for a particular prey category. A significant dietary overlap was calculated for three combinations and much higher in the combination made between Heterotis niloticus and L. bynni (α=0.91) from the Gelegu River. Ontogenetic and seasonal dietary variations were encountered on relative basis for a particular prey, not a complete shift from one prey to another. The fishing communities of the ALNP are using different piscicides for fishing; however B. aegyptiaca is a widely used and effective poisonous plant. A 96 h static toxicity bioassay in ponds was carried out to examine fish responses and to determine the median lethal concentration (LC50) of B. aegyptiaca stem bark aqueous extract on adults of Brycinus nurse, L. bynni and Labeobarbus intermedius. Experimental fish were exposed to piscicide extracts of 0.0 (control), 15.0, 17.5, 20.0, 22.5, and 25.0 mgL-1. Fish exposed to these extracts except the control showed symptoms of toxicity. These responses were specific to species and level of concentration. The 96 h LC50 value for the different test fishes were 18.832, 20.720 and 20.724 mgL-1 for L. bynni, L. intermedius and B. nurse, respectively. Based on the present investigation, applying B. aegyptiaca extract causes lethal toxic effects on different fishes even at low concentrations and hence, indiscriminate use of the plant for fishing should be discouraged and regulated to protect fish biodiversity lose in the ALNP area. The riverine fisheries of the ALNP is small-scale only dominated by individual fishers who owned mono-filament and hook fishing that provided livelihood, income and employment to full-time, part-time and occasional fishers. The Amhara National Regional State should take a prime responsibility related to infrastructure organization, controlling and enforcing of poison fishing and handling the ethnic based conflict arising due to resource utilization for sustainable use and development of the fisheries in the ALNP.Item Fish Biology and Fishery Management of Commercial Stocks in a Tropical Rift Valley Lake, Lake Langeno, Ethiopia(Addis Ababa University, 2018-03-05) Temesgen, Mathewos; Getahun, Abebe (Professor); Lemma, Brook (Professor)The study of status and trends of fish and fisheries in Lake Langeno (also known in the literature as Langano), Ethiopia was conducted from March 2014 to February 2016. The basis for this study was that fish stocks were subjected to uncontrolled fishing over many years and available data on the status and trends of fishes in the lake has become unreliable for management and sustainability of the sector. In order to examine the diversity, habitat preference and seasonal distribution, spatial and seasonal data were collected from six different sampling sites by using gillnets of various mesh sizes and long lines. Data were analyzed by Canonical Correspondence Analysis (CCA), SPSS software and by various descriptive statistics. The results indicate physico-chemical parameters showed no significant spatial variation, but high seasonal variation. A total of seven fish species dominated by family Cyprinidae were identified (H’=1.264). Carassius carassius, was not reported in previous studies, now comprise 0.64% of the total collected specimens. All the fish species were collected from all of the sampling sites, except at one site (Middle), where Carrasius carassius and Garra dembecha were absent. Index of relative importance (IRI) was essentially similar for all the sampling sites, but differed in the relative importance of each species with the high importance of Oreochromis niloticus. Principal Component Analysis (PCA) did not produce distinct habitat-associated species patterns across the sampling sites. However, temperature and depth seemed to be the key environmental factors determining fish community structure in the lake. The results showed that the composition of the fishes has undergone some changes during data collection from what was reported in the literature. The Length-weight relationships of O. niloticus, E. paludinosus, C. gariepinus, L. intermedius and C. carpio were curvilinear (b=2.872, 2.554, 2.823, 2.771 and 2.919, respectively), and statistically significant (p>0.05) except for Enteromius paludinosus. For both sexes, the mean Fulton Condition Factor values of Oreochromis niloticus, B. paludinosus, Clarias gariepinus, Labeobarbus intermedius and C. carpio were 1.77 }0.37, 1.06 }0.44, 0.60 }0.5, 1.33 }0.44 and 1.47 }0.83, respectively. A better body condition was recorded in the dry seasons for all species except for O. niloticus. All fish species had relatively smaller maximum size and poor body condition than what was reported for fishes in most of the Ethiopian water bodies. Females were more abundant than males for all fish species, and the sex ratio of O. niloticus (1.13:1)and E. paludinosus (1:.24:1) was significantly different from the hypothetical distribution of 1:1 (χ2, p<0.05. The identified peak breeding time was April- June, May-July, June-July and March-May for O. niloticus, C. gariepinus, L. intermedius and C. 5 carpio, respectively. Their respective length at L50 for females and males during these breeding times were 16.4 cm & 15.8 cm TL, 28.5 cm & 29.5 cm TL 30.5 cm & 29.5 cm FL and 28.2 cm & 27.6 cm FL. The mean fecundity of these fish species were 463.83 }114, 141,466 }40,982, 3,055 }2,234 and 105,631 }46,680, respectively. The results also showed significant seasonal variations of GSI for all fish species (ANOVA, P< 0.05). In addition, seven food items, namely phytoplankton, zooplankton, insects, detritus, macrophytes, fish parts and nematodes were identified from the stomach contents of O. niloticus. Phytoplankton was the main food grazed followed by detritus, zooplankton and macrophytes. The other food items were occasionally and randomly consumed. The volumetric contribution of these food items showed high variation in the study months (p<0.05). Phytoplankton and detritus were the dominant food items in the dry season and zooplankton and macrophytes were the highest in the wet months. The contribution of phytoplankton, zooplankton and insects were slightly high in small sized groups (<10 cm), whereas detritus, macrophytes and fish parts were the highest in larger size groups (>20 cm). Generally, food items of plant origin dominated the stomach contents, typically associated with less protein content than food item of animal origin. The result also showed that the lake supported small-scale beach seine fishery for small income generation and alternative employment opportunity of fishermen. The catch composition was dominated by O. niloticus (87.58%) followed by C. gariepinus (5.89%). Fisheries value chain was also developed and major related issues were addressed, fishers’ perceptions about the resources condition and management status were identified and discussed. Generally, the total annual fish production from the lake was estimated to be 1,137.67 tonnes/ year, and the mean gross annual revenue was about 8,622,158 ETB. Extrapolation of annual production and annual revenue from the sector showed a significance variation among the landing facility owners and those that do not have landing facilities (ANOVA, p<0.05), and between the fulltime and part time fishermen (ANOVA, p<0.05). The estimated annual per capita consumption of fish/ person was about 23.65 kg. The majority of the fishermen had positive attitude towards the fish resources, but due to lack of knowledge and follow up, the current harvest system and fishing methods put these resources at risk. Therefore, appropriate management action should be in place in order to sustain the fish resources in Lake Langeno.Item Fish Biology and Fishery Management of Commercial Stocks in a Tropical Rift Valley Lake, Lake Langeno, Ethiopia(Addis Ababa University, 3/5/2018) Temesgen, Mathewos; Getahun, Abebe (Professor); Lemma, Brook (Professor)The study of status and trends of fish and fisheries in Lake Langeno (also known in the literature as Langano), Ethiopia was conducted from March 2014 to February 2016. The basis for this study was that fish stocks were subjected to uncontrolled fishing over many years and available data on the status and trends of fishes in the lake has become unreliable for management and sustainability of the sector. In order to examine the diversity, habitat preference and seasonal distribution, spatial and seasonal data were collected from six different sampling sites by using gillnets of various mesh sizes and long lines. Data were analyzed by Canonical Correspondence Analysis (CCA), SPSS software and by various descriptive statistics. The results indicate physico-chemical parameters showed no significant spatial variation, but high seasonal variation. A total of seven fish species dominated by family Cyprinidae were identified (H’=1.264). Carassius carassius, was not reported in previous studies, now comprise 0.64% of the total collected specimens. All the fish species were collected from all of the sampling sites, except at one site (Middle), where Carrasius carassius and Garra dembecha were absent. Index of relative importance (IRI) was essentially similar for all the sampling sites, but differed in the relative importance of each species with the high importance of Oreochromis niloticus. Principal Component Analysis (PCA) did not produce distinct habitat-associated species patterns across the sampling sites. However, temperature and depth seemed to be the key environmental factors determining fish community structure in the lake. The results showed that the composition of the fishes has undergone some changes during data collection from what was reported in the literature. The Length-weight relationships of O. niloticus, E. paludinosus, C. gariepinus, L. intermedius and C. carpio were curvilinear (b=2.872, 2.554, 2.823, 2.771 and 2.919, respectively), and statistically significant (p>0.05) except for Enteromius paludinosus. For both sexes, the mean Fulton Condition Factor values of Oreochromis niloticus, B. paludinosus, Clarias gariepinus, Labeobarbus intermedius and C. carpio were 1.77 }0.37, 1.06 }0.44, 0.60 }0.5, 1.33 }0.44 and 1.47 }0.83, respectively. A better body condition was recorded in the dry seasons for all species except for O. niloticus. All fish species had relatively smaller maximum size and poor body condition than what was reported for fishes in most of the Ethiopian water bodies. Females were more abundant than males for all fish species, and the sex ratio of O. niloticus (1.13:1)and E. paludinosus (1:.24:1) was significantly different from the hypothetical distribution of 1:1 (χ2, p<0.05. The identified peak breeding time was April- June, May-July, June-July and March-May for O. niloticus, C. gariepinus, L. intermedius and C. 5 carpio, respectively. Their respective length at L50 for females and males during these breeding times were 16.4 cm & 15.8 cm TL, 28.5 cm & 29.5 cm TL 30.5 cm & 29.5 cm FL and 28.2 cm & 27.6 cm FL. The mean fecundity of these fish species were 463.83 }114, 141,466 }40,982, 3,055 }2,234 and 105,631 }46,680, respectively. The results also showed significant seasonal variations of GSI for all fish species (ANOVA, P< 0.05). In addition, seven food items, namely phytoplankton, zooplankton, insects, detritus, macrophytes, fish parts and nematodes were identified from the stomach contents of O. niloticus. Phytoplankton was the main food grazed followed by detritus, zooplankton and macrophytes. The other food items were occasionally and randomly consumed. The volumetric contribution of these food items showed high variation in the study months (p<0.05). Phytoplankton and detritus were the dominant food items in the dry season and zooplankton and macrophytes were the highest in the wet months. The contribution of phytoplankton, zooplankton and insects were slightly high in small sized groups (<10 cm), whereas detritus, macrophytes and fish parts were the highest in larger size groups (>20 cm). Generally, food items of plant origin dominated the stomach contents, typically associated with less protein content than food item of animal origin. The result also showed that the lake supported small-scale beach seine fishery for small income generation and alternative employment opportunity of fishermen. The catch composition was dominated by O. niloticus (87.58%) followed by C. gariepinus (5.89%). Fisheries value chain was also developed and major related issues were addressed, fishers’ perceptions about the resources condition and management status were identified and discussed. Generally, the total annual fish production from the lake was estimated to be 1,137.67 tonnes/ year, and the mean gross annual revenue was about 8,622,158 ETB. Extrapolation of annual production and annual revenue from the sector showed a significance variation among the landing facility owners and those that do not have landing facilities (ANOVA, p<0.05), and between the fulltime and part time fishermen (ANOVA, p<0.05). The estimated annual per capita consumption of fish/ person was about 23.65 kg. The majority of the fishermen had positive attitude towards the fish resources, but due to lack of knowledge and follow up, the current harvest system and fishing methods put these resources at risk. Therefore, appropriate management action should be in place in order to sustain the fish resources in Lake Langeno.Item Fish Diversity and Production in Tekeze Reservoir, Tekeze Basin, Ethiopia(Addis Ababa University, 2020-11-15) Gebru, Shibabaw; Getahun, Abebe (Professor); Teferi, Mekonnen (PhD)Ethiopia has several freshwater systems from where plenty of aquatic foods could be produced. However, due to poor management practices, the contribution of the fishery to the country’s economy is by far little. Tekeze Reservoir has potential in fish production, but little or no detailed and documented scientific information is available about the fish biology and fishing activities. Consequently, the fishery of the reservoir is poorly understood and its sustainability is unpredictable. Therefore, this study aimed to contribute to the management of the reservoir fishery by providing scientific information for sustainable utilization of the aquatic resources. Data was collected using various methods over a period of two years and analyzed using various statistical tools and methods. Fifteen fish species were identified in the present study. The index of relative importance (%IRI) of the key species in the reservoir includes Oreochromis niloticus, (35.5%), Bagrus docmak (22.6%), Labeobarbus intermedius (20.5%), Labeo niloticus (10.6%) and Labeo forskalii (10.2%). However, Clarias gariepinus, Labeobarbus nedgia, Raiamas senegalensis, Labeobarbus crassibarbis, Hetrobranchus longifilis, Garra dembeensis, Bagrus bajad, Labeobarbus bynni, Labeo cylindricus and Labeobarbus beso constitute below 1% of the total catch. The river mouth habitats contributed the most catch composition, while the pelagic habitats contributed the least. Length-weight relationship of O. niloticus, L. intermedius and B. docmak were best expressed by the equations TW = 0.014TL3.054 (r2 = 0.9743, P = 0.0001), TW = 0.0196SL2.9493 (r2 = 0.9609, P < 0.0001) and TW = 0.0098SL3.0819 (r2 = 0.9678, P < 0.0001), respectively. The overall mean condition factor was found to be 1.44±0.01 for O. niloticus, 1.88±0.02 for L. intermedius and 0.94±0.01 for B. docmak. The feeding habit of O. niloticus, L. intermedius and B. docmak indicated that both plant and animal origin food items were consumed by the species. However, phytoplankton for O. niloticus, detritus for L. intermedius, fish and fish remains for B. docmak were the most important food types. Although the proportion was different, the studied fish species consumed all food items in all seasons of the study period. In some size classes of O. niloticus and B. docmak, complete ontogenic shifts were observed, but all food items in different proportions were ingested by L. intermedius. The overall sex ratio (female: male) of O. niloticus and B. docmak was significantly deviated from the hypothetical distribution of 1:1(P iv < 0.001). However, the sex ratio of L. intermedius did not significantly deviated. Size (TL) at first maturity of O. niloticus was 24.2 cm for females and 24.87 cm for males. The size at maturity for L. intermedius and B. docmak (SL) were 20.84 and 27.42 cm for females and 22.05 and 26.79 cm for males, respectively. The mean absolute fecundity of the species was 1,513, 4,788 and 92,321 eggs for O. niloticus, L. intermedius and B. docmak, respectively. The studied species had extended spawning period, from July to October with peak spawning in August for O. niloticus and B. docmak and in September for L. intermedius. Labeobarbus intermedius preferred riverine habitats while O. niloticus and B. docmak prefer the littoral habitat for breeding. The catch per unit effort of the fishery ranged from 15.98 kg/boat/day to 3.26 kg/boat/day. The extent of immature fish harvesting by the commercial catch indicated that O. niloticus (33.32%), L. intermedius (37.72%) and B. docmak (42.17%) were caught before they attain their first sexual maturity. A total of 48 fishery associations with 3,174 members were distributed in the reservoir. The average age of the fishers was close to 30 and about 94% of them were males. The majority (67%) of the fishers were full-timers with the average fishing experience of 4 years and 64% of them had taken formal education. Gillnets and longlines were the commonly used fishing gears and operated for 24 hours in the reservoir. Addis Ababa and Mekelle were the major market destinations for filleted fish, but Shire and Humera towns were for the gutted and sun-dried fishes. The fishery contributed to the rural communities as source of nutrition and food security, employment opportunity and source of income. However, due to poor management practices, illegal fishing activities and overexploitation of the resources, the fish production and fishery business have declined. Therefore, to sustain the production and productivity as well as the socio-economic contribution of the reservoir fishery, the federal government and the two regional states such as Tigray and Amhara Regional States should take a responsibility to address the major problems that cause the depletion of the stock in the reservoir.Item Habitat Use and Characterization of Young-of-the-Year (YOY) Labeobarbus Spp. in Gumara River, Lake Tana Sub-Basin, Ethiopia(Addis Ababa University, 2020-01-01) Erarto, Felegush; Getahun, Abebe (Professor); Mengist, Minwyelet (PhD); Anteneh, Wassie (PhD)Information regarding habitat requirements of different fish species at early life stages plays important roles for monitoring, protecting or managing fish populations and their habitats. Although spawning migration of Labeobarbus species to Gumara River has been reported by various studies, organized information on abundance, distribution, habitat use and preference of young-of-the-year were not available. Such information is very important for the management of the declining endemic Labeobarbus species of Lake Tana. So, the aim of this study was to investigate abundance, habitat use and characterization of young-of-the-year of the Labeobarbus species. Habitat use and characterization of young-of-the-year of the migratory riverine spawning Labeobarbus species of Lake Tana were studied in Gumara River and its tributaries from November 2018 to April 2019. Physico-chemical parameters were measured using probes and there were significant variation (p<0.05) among sampling sites. Fish sampling was conducted using point abundance sampling by electrofishing across banks and mid-channel to cover all habitat types. A total of 3,880 fish specimens were collected from all sampling sites. Out of the total catch, about 24.36% of the contributions were from young-of-the-year of the Labeobarbus species. The abundance of fishes varied between sampling months and sites and this might be attributed to the differences in physico-chemical parameters, substrate type, altitude, depth and velocity of the water. The Shannon’s index (H'=1.21) and evenness value (J'=0.53) in Gumara River indicate moderate pollution and uniform distribution of individuals. Among the six sampling sites, the highest (H' = 1.30) and lowest (H' =0.94) diversity index were recorded at sites in the upstream near to Wanzaye hot spring and below the bridge, respectively. In terms of mesohabitat, the species diversity and evenness were higher in riffle (H' = 1.25, J' = 0.57) than run (H' = 1.15, J' = 0.55) and the pool (H' = 1.11, J' = 0.50). The result showed that the species prefer at a mesohabitat scale riffles and later pools in Gumara River and this is mainly due to the drying of riffle habitats during the dry season and hence forced to shift to pool habitats. At a microhabitat scale also juveniles prefer sites with moderate water depth, low to medium water velocity; gravel substrate type and vegetation cover. Pool habitat served as the only option until the next rainfall comes. Therefore, emphasis should be given to the factors which may lead to the collapse of the pool habitats, especially water abstraction through pumping for small scale irrigation. The detailed study on the habitat modeling and the habitat suitability index should be done for proper management of the Lake Tana fishery.Item The Impact of Shark Liver Oil Trade on the Conservation and Management of Threatened Shark Species in Zanzibar, Tanzania.(Addis Ababa University, 2021-06-14) Mirobo, Frank; Getahun, Abebe (Professor)For decades shark fishery in the world has been one of the economic activities to most fishing villages including those in Zanzibar, Tanzania. The trade of live sharks and shark products has been one of the international trades that pose a major threat in the existence of sharks worldwide. However, information on the impact of shark liver oil trade in the conservation and management of threatened shark species in Zanzibar, Tanzania is so far lacking. This study aimed to determine the impact of the shark liver oil trade in the conservation and management of threatened shark species in Zanzibar, Tanzania. The study used focus group discussion, structured and unstructured questionnaires, key informant interviews, and shark oil sampling. Additionally, acidic value and viscosity of the shark liver oil and shark catch landings were also used as sources of data for this study. The findings of this study reveal that species like Tiger shark, Sickletin lemon shark, Bull shark, Giant guitarfish, and Shortfin mako shark were the most prone species to shark liver oil trade. Additionally, shark oil of Giant guitarfish was the most preferred shark oil for wooden boat maintenance with viscosity of 10.3 m2 s−1 and 70.5 mg NaOH/g acid value however, less in quantity production of 60 liters of shark liver oil. Whilst, tiger shark with 360 liters of shark liver oil, was the shark specie with higher quantity of shark liver oil. However, elasmobranchs catch landings have increased up to 1.7 million tons per year in 2020 which implies the continued exploitation of elasmobranchs in the Island compared to other years after the banning of production and trading of shark products in Zanzibar. This has been accelerated due to verbal restriction of shark products, less enforcement of the rules, increase in the foreign fishing vessels and unaccountability on the part of government officers. However, banning of shark products trade has affected the livelihood of shark fishermen by 92%, hence low wages gain in the trade and fishermen struggles in providing for their family needs. Overall, the continued trading of the shark liver oil affects the conservation and management of all IUCN listed threatened shark species in Zanzibar as majority of them are also overexploited for meat and fin trade in the region. Results of this study show that besides the shark fin and meat trade, shark liver oil also affect the shark conservation and is a contributing factor. Strong management and conservation strategic plan and use of shark oil alternatives are highly required to regulate the status of shark species prone to this kind of trade in Zanzibar, Tanzania.Item The Nile Tilapia (Oreochromis Niloticus L. 1758) of Three Ethiopian Rift Valley Lakes Physico-Chemical Conditions Phenotypic and Reproductive Characters and Response to Elevated Fry Rearing Temperature(Addis Ababa University, 2021-12-28) Endebu, Megerssa; Getahun, Abebe (Professor); Tessema, Misikire (PhD)Fishery and aquaculture development along with sustainable use of natural resources play significant role in alleviating the problems of nutritional insecurity and environmental degradation in Ethiopia. The ecological status of Ethiopian Rift Valley lakes; which provide substantial economic, environmental and social benefits across diverse ecological settings; and the potential of the Nile tilapia, Oreochromis niloticus (L. 1758) populations in aquaculture development were not comprehensively studied. This study was thus undertaken to assess the current and past physico-chemical conditions of Lakes Chamo, Koka and Ziway, phenotypic and reproductive characters of O. niloticus populations of the lakes, and potential of the fish populations for aquaculture development. Field, laboratory and experimental data were obtained using standard methods over a period of three years, and analyzed using various computations, and compared against previous records and standards. The study demonstrated that water physico-chemical parameters varied significantly between seasons, and within and between the lakes. The findings have shown that some of the parameters were higher than previously reported levels. Anthropogenic associated factors including water turbidity, soluble reactive phosphorus, and nitrate-N concentrations varied among the lakes and across seasons. Invasion of water hyacinth and wetland vegetation cover also varied considerably across the lakes. Phenotypic and reproductive characters, and response to elevated fry rearing temperature of the three O. niloticus populations from the three lakes were also investigated. There were significant differences (p ≤ 0.05) in most of the morphometric character indices, meristic counts, mean length and weight, Fulton's condition factor, length at first sexual maturity (L50), absolute fecundity, peak breeding seasons and response to heat treatment among the three O. niloticus populations. The current values of some of the parameters, like L50, decreased from previous reports, indicating urgent need for implementation of proper fishery management. Possessing desired phenotypic and reproductive qualities in aquaculture, populations of Chamo followed by Koka appear to be potentials for further genetic improvement. Further research is required to investigate whether the fish populations could maintain those characters in pond cultures. To improve sex reversal efficiency by heat treatment, sensitive individuals can be selected and their degree of sensitivity can be improved through continuous selection of progenies from temperature sensitive parents. Generally, there is an urgent need for proper agricultural practices, proper municipal and industrial waste management practices, protection of wetland vegetation and delimitation of the lakes' buffer zones to sustain the services of the lakes.Item Status of Fish Supply, Marketing and Consumption in Nifas Silk Lafto and Lideta Sub-Cities, Addis Ababa, Ethiopia(Addis Ababa University, 2019-09-09) Gedafa, Wudinesh; Getahun, Abebe (Professor)This study aimed at assessing status of fish supply, marketing and consumption in Nifas silk Lafto and Lideta sub-cities in Addis Ababa, Ethiopia. Both primary and secondary data were used for the assessment. Questionnaires and interviews were employed as a means of primary data collection techniques. Most individual fishers and cooperatives in one of the supply areas (Lake Ziway) are youngsters with low educational level and large family size. They are engaged in fishing for income generation. The commercially important fish species are tilapia, catfish, Labeobarbus and carp though there is scarcity of all species. Long lining fishing gears and gill nets were predominantly used. The number of fish catch per day per fisherman mostly ranges 10-20kg whereas those of cooperatives members range from 30 to 40 kg. The market chain begins with a producer (fishermen) and terminates with consumers. The fish supply constraints in this production area are mismanagement of the lake, lack of modern fishing instrument and storage facilities. The majority of fish traders in Nifas Silk Lafto and Lideta sub-cities were involved in fish trading for income generation. They bring fish from production area by using cold storage vehicle as means of transport. About 60.34% Nifas silk Lafto and 68.96%Lideta sub-cities traders choose tilapia fish species and most of them present in fillet form. The market constraints show seasonal fluctuations of fish demand and lack of fish. Restaurant workers mainly buy fish from traders by making tilapia their number one choice. Though fish consumption has high nutritive value and healthy benefits, most of the community members in both sub-cities prefer beef to fish; the consumption trend is relatively high during fasting seasons. Those who consume fish choose fried fish than the other forms. Promotion of fish production and awareness creation on the nutritive value and health benefits of fish consumption are required to scale up fish demand and supply in both sub-cities.Item Studies on the Limnology, and Biology of Nile Tilapia, Oreochromis Niloticus L., in a Tropical Soda Lake, Lake Shala, Ethiopia(Addis Ababa University, 2021-05-02) Wagaw, Solomon; Mengistou, Seyoum (Professor); Getahun, Abebe (Professor)Lake Shala is the deepest, alkaline lake in Ethiopia and is a vital resource having considerable esthetic, economic, scientific and ecological values. However, the lake is under pressure from various anthropogenic activities and climatic change. There is also a plan to expand the Abijata Soda Ash plant to Lake Shala. The purpose of this study was to assess the spatial and seasonal dynamics, and long-term trend of abiotic factors and biological communities in the lake. Physicochemical and biological data were collected from four sites every month from January to December 2018. All physicochemical factors exhibited significant variation among sites and between seasons (ANOVA, P < 0.05), except DO, which showed only seasonal variation. Compared with previous studies, long-term increasing trend in pH, alkalinity, salinity, electrical conductivity, NO3-N, NH3-N, SRP and TP, and decreasing trend in SiO2 were observed. These changes might be due to the high evaporation rate in the region, precipitation, accumulation of solutes and saline surface runoff from its degraded catchments. The phytoplankton community in Lake Shala showed changes with time. During this study, 72 phytoplankton species belonging to Bacillariophyta (55 taxa), Chlorophyta (7 taxa), Cyanophyta (6 taxa), Euglenophyta (2 taxa), Charophyta (1 taxon) and Dinophyta (1 taxon) were recorded. The previous dominance of Cryptophytes in the lake has been replaced by diatoms. The lake also lacked Arthrospira fusiformis, but now a few specimens were recorded many times. Zooplankton community structure of Lake Shala (32 species, belonging to rotifers, copepods and cladocerans) has also changed over time, benthic harpacticoids (Nitocra lacustris) were replaced by small-bodied and generalist-v feeders rotifers (genus Brachionus). Such ecological shifts in phytoplankton and zooplankton communities may be associated with physicochemical changes and ‘atelomixis’ brought about by unusual mixing behavior in deep, tropical lakes. Based on RDA analysis, most phytoplankton and zooplankton species were strongly influenced by nutrients, salinity and electrical conductivity. The macro-invertebrate community of Lake Shala, was constituted by a few (21) taxa belonging to the Diptera (7), Gastropoda (4), Hemiptera (3), Coleoptera (2), Oligochaeta (2), Argulidae, Arachnida and Corydalidae. Compared with previous data, shifts in macro-invertebrate community structure were observed over the years. The shift might be due to the changes in the water chemistry and recession of the lake littoral zone. The macro-invertebrate taxa richness and abundance were significantly affected by locality (P < 0.05), the two shore sites having significantly higher taxa richness and the opposite was true for abundance. Most families were absent from the open water stations and when present, represented by Diptera (Ceratopogonidae and Chironomidae) and Oligochaeta (Tubificidae and Naididae), which were correlated strongly with depth, DO, EC and alkaline-salinity of the lake. These abiotic factors have presumably become altered in the lake due to undetermined stressors. Previous studies did not report the ecology and biology of fish from Lake Shala and this study is the first to document the biology of tilapia from this lake. Oreochromis niloticus had a curvilinear growth pattern (TW = 0.0104TL3.19, R2 = 0.98, n = 343). The condition factor between sex categories (ANOVA, P > 0.05) and sex ratio from the hypothetical distribution of 1:1 (χ2 = 0.47, P > 0.05) were not significant. The breeding seasons, rainy (July) and dry (February) coincided with the increase in phytoplankton abundance and biomass (Chl a). The fecundity ranged between 240 and 1,642 eggs per fish, with a mean fecundity of 806 eggs and correlated with the length and weight of the fish. Analysis of the stomach revealed that 226 (65.9%) fish contained different food items, while 117 (34.1%) had empty stomachs. O. niloticus mainly fed on phytoplankton and had phytoplanktivorous feeding habits. Bacillariophyta was identified as the most desired phytoplankton item. The prey items and food habits of O. niloticus varied significantly among size classes (ANOVA, P < 0.05) and seasons (t-test, P < 0.05). Such variations might be associated with seasonal availability of natural food, habitat, and morphological and physiological changes such as increase in the length of the gut and acidity as the fish grow. This study is the first comprehensive study on the limnology, and biology of O. niloticus in Lake Shala. Lake Shala is located in the center of economic development pressure and the physical environment and the biota of the lake are continually changing. Such ecological changes in this deep lake might be due to anthropogenic activities around the lake catchments and internal limnological dynamics (atelomixis). However, continuous investigation on physical environment and biodiversity assessment in Lake Shala is necessary to evaluate the ecological impacts of the upcoming soda ash factory and other external impacts on the limnology of the lake ecosystems.Item A Study on Status of Fish Production & Marketing in Lake Ziway, Ethiopia(Addis Ababa University, 2019-08-08) Kassaw, Getnet; Getahun, Abebe (Professor)Lake Ziway, which is the third largest lake in Ethiopia, is the most overexploited lake for the use of fishery, irrigation, recreation, road construction and tourism .The primary data was collected during, June 7-21, 2019 in Adami-Tulu Jido Kombolcha district at Wafeqo landing site. This study had attempted to assess fishermen’s socio-demographic nature in relation to fish production, market condition and other means of income, determine factors of fish production and possible lake management measures in Lake Ziway. Descriptive statistics, one way ANOVA Tukey post hoc model and pearsons’ chi-square independence test were used to analyze the data using IBM SPSS version 22. A total of 104 fishermen (100% male), 1 member of fish processor enterprise (time keeper) and 3 key informants from Adami-tulu animal and fish development office and Batu Fish and Other Aquatic Life Research Center were involved in data collection. Among the respondent fishers, 94 (90.3%) were members of the cooperatives while 10 (9.7%) were not. The livelihoods of people were known to directly depend on fishing activities around Lake Ziway including that of the interviewed fish processor. The study found out that fishing time, fishing instrument, means of boat type, mode of fishing, level of education, access to training, and age of fishermen had a direct effect on the amount of fish catch. Night time fishing had maximum amount of fish catch in terms of fishing time. Besides, fishermen who had better level of education and access to training used better means of transportation and fishing instruments. It was also indicated that there is high fish catch by using beach seine even if it had got legal restrictions with respect to fishing gears. Fishermen were not directly benefited from the market system. In addition to these, the study found out that illegal fishing, unauthorized use of fishing gears, overfishing, excessive use of the lake’s water for irrigation and road construction, emission of chemicals from the nearby flower farm and motor oil discharges are the major challenges for the existence of the lake. Generally the absence of effective lake management system accelerated the decline of the fish resources in Lake Ziway. To overcome these adverse impacts on the fish resource, there should be continuous professional follow up and trainings, diversification of employment for youth and organization of individual fishers into fishermen association.Item The Water Quality Of Floriculture Effluent and Its Effect on Oreochromis Niloticus and Cyprinus Carpio In Aquaria: The Case of Lake Ziway, Ethiopia(2018-03-01) Teshome, Elsa; Getahun, Abebe (Professor); Mengistou, Seyoum (Professer)Floriculture industry is a booming sector in Ethiopia and is spreading throughout the country. It is believed to create pressure on biodiversity through the release of hazardous chemicals in the form of fertilizers, pesticides and disposal of untreated wastes which contaminates the water body and could be harmful to fishes and other aquatic organisms. Previous studies in Lake Ziway imply that floriculture industries are major sources of chemical substances resulting in deterioration of water quality that affect fish species in the lake. The present experimental study aimed at assessing the water quality of the floriculture effluent discharge that reaches Lake Ziway and its impact on the survival, behavior and histology of Oreochromis niloticus and Cyprinus carpio in aquaria with 0%, 25%, 50%, 75% and 100% concentrations of the effluent. Histological changes in gills, kidney and liver were examined by using light microscope to evaluate the health of C. carpio and O. niloticus subjected to the effluent, which lasted for 15 days. The results of all physicochemical analysis indicated that all parameters in the effluent and lake water were within the range of maximum permissible limits (MPL) set by Environmental Protection Authority (Ethiopia-EPA, 2003) and FAO, WHO guideline for the maintenance for fisheries and aquatic life. But, measured values of some parameters such as pH, conductivity, total phosphorus and soluble reactive phosphorus indicate the pollution status of Lake Ziway. There were no behavioral alterations and deaths observed in the exposed and control treatments of both fish species during the experimental period. In the result of the histology sections, the degree of lesions were comparatively increased with the increase in effluent concentration, while the alteration in the liver and kidney of O. niloticus was higher than C. carpio, this indicates that the floriculture effluent may be one of the problems for the decrease in catch size of O. niloticus than C. carpio. The gills, livers and kidneys of control groups exhibited a normal structure. Therefore, the effluent discharge from Sher Ethiopia flower industry has affected the water quality and ecology of the lake; Lake Ziway becoming less suitable for fishes. Actions should be taken before the once precious fresh water lake turns out to be seriously polluted and fishes and aquatic organisms are exposed to severe pollution.