Abstract
The high cost of fish feed has affected the culturing of tilapias and sharptooth catfish in Africa. However, Africa is well endowed with terrestrial insects that can potentially replace fishmeal in the diets of fish. In this paper, the nutritional index, availability, and cost of selected insect meals are compared. The SOLVER function in Excel was used to formulate least-cost diets of Musca domestica, Gryllotalpa africana, Schistocerca gregaria, Macrotermes natalensis, and Gonimbrasia belina. The crude protein levels of all the insects were above 50% and met the requirements of both fish species. The essential amino acid index (EAAI) was highest in M. domestica (3.2613). Except for M. natalensis, all the insect meals met the fat requirements for tilapias and sharptooth catfish. The most available insects were S. gregaria and M. domestica. Feed value was highest in fishmeal (15.62) followed by M. domestica (15.52). A meta-analysis of the effects of replacing fishmeal with insect meal on growth performance of tilapias and sharptooth catfish was also carried out. The effect summary for the specific growth rate was significant whereas the effect summary for the food conversion ratio was not significant. The relationship between fishmeal replacement levels and response ratio showed wide scatter. It was thus not possible to determine the optimum replacement level. Musca domestica is recommended in the replacement of fishmeal.
Highlights
Tilapias and sharptooth catfish are two of the most widely cultured fish species in Africa [1]
Except for M. natalensis, all the other insect ingredients met the fat requirements for O. mossambicus and C. gariepinus
The highest essential amino acid index (EAAI) was recorded in M. domestica
Summary
Tilapias and sharptooth catfish are two of the most widely cultured fish species in Africa [1]. Since O. mossambicus opportunistically feeds on insects in nature, it can be assumed that it is preadapted to utilizing insect-based diets. Clarias gariepinus (sharptooth catfish) is the most widely cultured clariid in Africa. It is known to be an omnivorous fish that feeds on a variety of food items such as fish, insects, phytoplankton, zooplankton, macrophytes, and detritus [6, 7]. Spatary et al [8] identified more than 50 species of animals and plants from the intestines of one population of C. gariepinus in Lake Kinneret, Israel, and these included fish, insects, and zooplankton. It is clear from the literature that insects constitute an important food item in the diet of sharptooth catfish. It can be assumed that sharptooth catfish is preadapted to utilizing insect-based diets
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