Performance of African Catfish (Clarias Gariepinus, Burchell,1822) Larvae Fed Spirulina and Redworms as Protein Alternative in Formulated Diets

Abstract

The contribution of aquaculture to food security and employment cannot be overemphasised. However, the limited availability of quality seed and feed has prevented it from realising its full potential. A vital component of fish feeds is aquatic animal protein sources like fishmeal and freshwater shrimp meal (Caridina nilotica). Continued use of aquatic animal proteins in fish feed further decreases capture fisheries catches. Alternatives to aquatic protein sources in the feed industry like soybean meal, are expensive and in competition with human food. Feed prices have skyrocketed and have made fish larvae' nutrition a hindrance to aquaculture development. This study investigated the growth, digestive capacity and stress tolerance of Clarias gariepinus larvae fed on Spirulina platensis or Eisenia fetida in formulated diets. The study was conducted at the University of Nairobi, Department of Biology under controlled conditions. Seven diets were formulated to be approximately iso-nitrogenous and iso-caloric. Spirulina platensis or Eisenia fetida partially replaced Caridina nilotica at 25%, 50%, and 75% and control of 100% Caridina nilotica to give the seven diets. In addition, a commercial diet (Gemma Micro, Skretting Co. Netherlands) with 100% fishmeal was used to compare the performance of formulated diets and what was available in the market. Clarias gariepinus larvae were artificially propagated and randomly stocked at 25 larvae per litre in 24 glass aquaria at 28 ℃. Larvae were fed at 20% of their body weight, decreasing to 10% at the end of week two at a frequency of five times a day. Fish in the aquarium were randomly assigned one of the eight experimental diets in triplicate. Larvae fed on these experimental diets were transitioned to fingerlings in the grow-out tanks at Makindi Fish Farm Muranga County, Kenya, to assess the effects of hatchery nutrition on growth. Fingerlings were fed on skretting and Raanan feeds at 5% body weight twice daily in grow-out tanks. Nutrient utilisation was determined by feed conversion ratio and protein efficiency ratio while weight gain, specific growth rate and survival determined larval growth performance. A partial cost analysis for all experimental diets was estimated...