~ 320 ~ International Journal of Fisheries and Aquatic Studies 2021; 9(6): 320-327 E-ISSN: 2347-5129 P-ISSN: 2394-0506 (ICV-Poland) Impact Value: 5.62 (GIF) Impact Factor: 0.549 IJFAS 2021; 9(6): 320-327 © 2021 IJFAS www.fisheriesjournal.com Received: 24-09-2021 Accepted: 26-10-2021 Michael KG Department of Fisheries, Modibbo Adama University of Technology, Yola, Nigeria Amos N Department of Fisheries, Modibbo Adama University of Technology, Yola, Nigeria Solomon K Department of Fisheries, Modibbo Adama University of Technology, Yola, Nigeria Corresponding Author: Michael KG Department of Fisheries, Modibbo Adama University of Technology, Yola, Nigeria Growth performance of Clarias gariepinus fingerlings fed varying inclusion levels of toasted African mesquite (Prosopis africana) seed meal Michael KG, Amos N and Solomon K DOI: https://doi.org/10.22271/fish.2021.v9.i6d.2618 Abstract Growth performance of Clarias gariepinus fed varying inclusion levels of toasted Prosopis africana seed meal was carried out for 40days in a plastic tank. African mesquite was toasted. 40% crude protein diets were formulated using Pearson square method in which African mesquite seed meal was included at varying levels of Diet 1 - 0%, Diet 2 - 5%, Diet 3 - 10%, Diet 4 - 15% and Diet 5 - 20% African mesquite seed meal. 100 Clarias gariepinus fingerlings were acclimatized for 24hours and stocked in 40 Liter circular plastic tank, each tank was duplicated and labeled according to the inclusion level. The initial weight and length were taken at the beginning of the experiment and also weekly to adjust the quantity of feed given to the fish at 5% body weight. Feeding was done two times a day (morning and evening). Water quality was measured and experiment monitored for daily mortality. The cost benefit analysis was also determined. The result of the experiment shows that the best weight gains (28.22±5.23 a ), specific growth rate (1.90±0.25 a ), feed conversion ratio (0.88±0.08 b ), relative growth rate (82.42±4.06 a ), protein intake (959.5±85.6), protein efficiency ratio (0.0045±0.00 a ), feed intake (24.7±2.20 a ) and gross energy (4.55±0.00) were from fish fed with Diet 5. The temperature, dissolved oxygen and pH were not significantly different (p≤0.05). The highest net production value with (28225.00±529.66 a ), and benefit cost ratio with (521.36±78.94 a ) were recorded in Diet 5. Based on findings from this research, 20% inclusion of Prosopis africana seed meal can replace soybean without affecting the profit of the farmers. Keywords: Prosopis africana, Clarias gariepinus, weight gain, specific growth rate, feed conversion ratio Introduction Good nutrition in animal production systems is essential to economical production of a healthy, high-quality product [1] . In fish farming (aquaculture), nutrition is critical because feed typically represents approximately 50 percent of the variable production cost. Fish nutrition has advanced dramatically in recent years with the development of new, balanced commercial diets that promote optimal fish growth and health. The development of new species-specific diet formulations supports the aquaculture industry as it expands to satisfy increasing demand for affordable, safe, high quality fish and seafood products [1] . One of the areas which the fisheries potential of Nigeria could be exploited is through aquaculture, the development and expansion of which would however depend mainly on many factors [2] . These include the availability of good quality and relatively inexpensive feed ingredients for the formulation of compounded food since supplement feed brings greater yields in ponds than if the fish were left to depend on natural (aquatic) food. Various feeds are used in culturing fishes to enhance adequate fish growth, reproduction and survival [2] . Soybean meal is the most extensively used plant protein source in livestock diets as it has a high crude protein content and a well-balanced essential amino acids profile [3] . However, inclusion of soybean in practical fish rations is constrained by its competitive use as a dietary protein source for human, livestock nutrition, use in bio-fuel, decline in national production and increasing costs have encouraged the search for a substitute [4] . Hence, it is important to evaluate the nutritive value of other inexpensive under-utilized plant protein sources that would replace soybean meal such as mesquite seed. Prosopis africana seed is among these abundant plants. It can be found growing wild in Nigeria and other parts of West Africa [5] . The fruits occur as pods which are dark brown cylindrical thick and hard shiny up to 15 x 3 cm with woody walls compartmented; about 10