The effect of a mixture of four indigenous bacterial genera composed of Bacillus, Pseudomonas, Acinetobacter and Flavobacterium on egg hatchability and larval viability of Clarias gariepinus was investigated. The fertilized eggs were distributed into glass Petri dishes (100 mm diameter) containing 50 ml of water at graded level of mixed indigenous probiotics ranging from 0-10(8) cells/ml. The incubation time increased from 17 hours at 0 cfu/ml to 22 hours at 10(8) cfu/ml. The mean hatching rate increased from 8.70% at 0 cfu/ml to 53.85% at 10(8) cfu/ml. The highest larval survival of 71.43% recorded at 10(8) cfu/ml where the highest hatching rate was observed, was significantly higher than the larval survival rate observed at the other concentrations. All yolk sac larvae at 0 and 10¹ cfu/ml died before the end of yolk sac period. These results imply that the incubation time, hatching rate and larval survival of Clarias gariepinus increased with increase in bacterial load of water up to 10(8) cells/ml, the highest dose employed. Further investigations are needed to establish the optimal and threshold doses.
Clarias eggs; incubation; rearing; indigenous probiotics; yolk sac larvae