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Spirulina platensis, Eisenia fetida, Caridina nilotica, Clarias gariepinus larvae, Fish larval nutrition, Protein alternatives
Profitable aquaculture depends on quality seed and fish feed used. The need to use significant amount of aquatic resource proteins in aquafeed presents economic and environmental challenges. Therefore, it is necessary to develop sustainable, cheaper, renewable and ecofriendly protein alternatives to replace aquatic resource proteins, hoping for their eventual elimination from larviculture. The current study evaluated Spirulina platensis and Eisenia fetida as dietary protein sources for Clarias gariepinus larvae (0.002g±0.04). Hundred percent Caridina nilotica in the control diet was partially replaced by either Spirulina platensis or Eisenia fetida at 25%, 50% and 75% to formulate six approximately isonitrogenous and isocaloric Clarias gariepinus larval diets (T1, 25%S. platensis +75%C. nilotica; T2, 50%S. platensis + 50%C. nilotica; T3,75%S. platensis +25%C. nilotica; T4,25%E. fetida + 75%C. nilotica; T5,50%E. fetida +50%C. nilotica; T6 ,75%E. fetida +25%C. nilotica). Diets were randomly assigned to 21 glass aquaria in triplicate. Twenty-five larvae per liter were randomly distributed into each aquarium, 48 hours after hatching. The larvae were fed at 20% body weight decreasing to 10% by fourth week of the experimental period, five times a day for eight weeks. Growth performance, nutrient utilization and survival response were evaluated in controlled culture conditions. Each diet formulation cost was also estimated. A combination of 50% Eisenia fetida and 50% Caridina nilotica performed significantly (p<0.05) better in growth, nutrient utilization and survival at a relatively low formulation cost. Possibly because of higher levels of methionine, lysine, isoleucine, leucine, valine, arginine, glutamic and phenylamine which are responsible for enhanced growth and survival. However, these parameters reduced in larvae fed on 50% Spirulina platensis and 50% Caridina nilotica due to higher crude fiber. Caridina nilotica can be replaced with either Eisenia fetida up to 75% or 25% of Spirulina platensis without negative effect on growth, nutrient utilization and survival.