Effect of Partial Replacement of Fishmeal with Duckweed (Lemna Spp.) Meal on The Growth Performance of Juvenile Nile Tilapia (Oreochromis Niloticus L.) in Tanks
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Date
2023
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Addis Abeba University
Abstract
One of the most essential components for optimum productivity in the aquaculture sector is the availability of quality fish feed. Fish meal is one of the most commonly used ingredients as a source of protein for fish feed. However, it is very expensive and is not easily available on the market. The present study therefore aims to determine the impact of partially replacing fishmeal with duckweed (Lemna spp.) on the growth performance of juvenile Nile tilapia (O. niloticus L.) in tanks. The feeding experiment was conducted from January to April 2023 at the National Fisheries and Other Aquatic Life Research Center (NFALRC), Sebeta, Ethiopia. The growth experiment was run in triplicate tanks in a greenhouse using three treatment diets with different inclusions of duckweed (DW) and one control diet. All four test diets were iso-nitrogenous (34.1–34.9% crude protein), including the control. Duckweed was added to three test diets at rates of 10% DW (T2), 20% DW (T3), and 30% DW (T4), replacing fishmeal, while the control diet (T1) had no duckweed at all. Using a complete randomized design, 360 O. niloticus were stocked in four treatments, each in three replicates. Stocked fish were acclimatized in tanks for two weeks before the start of the actual experiment. The results of the study showed that fish fed with 10% DW (T2) and 20% DW (T3) showed a better growth rate than the others. This indicated that increasing the amount of duckweed replacing fishmeal in the diet had a significantly (P < 0.05) better growth of juvenile O. niloticus up to 20% inclusion of duckweed. The tissue proximate composition of fish fed with 10% DW (T2) and 20% DW (T3) was found to be better than the other groups. From an economic view, 30% DW (T4) showed the lowest incidence cost (77.04) and had a higher profit index (0.57) followed by 20% DW(T3) with (77.82) incidence cost and profit index (0.51). This might be due to the higher inclusion the cheap duckweed replacing the most expensive fishmeal in the diet. In conclusion, a diet up to 20% inclusion rate of DW replacing fishmeal is suitable for juvenile Nile tilapia without affecting the growth of the fish.