Effect of zooplankton feeding frequency on the growth and survival of the African catfish, Clarias gariepinus (Burchell, 1822) early Larvae
Compared to other fish species, C. gariepinus fry needs quality live food after hatching and resorption of the yolk sac. An imported and costly Artemia cyst has been used as a source of live food for C. gariepinus hatcheries in Ethiopia. But imported Artemia cyst is very costly and cannot be afforded to sustain small scale hatchery business. An experiment that used local zooplankton species as a source of live food was conducted to determine whether it could be a replacement and its performance for growth and survival of C. gariepinus larvae. Local zooplankton groups from Lake Tana were inoculated and multiplied in zooplankton culture ponds fertilized with commercial fertilizer. Larvae with mean weight of 23 mg were stocked in 50 l aquarium at a stocking density of 2 larvae/l. Zooplankton were provided for larvae at a rate of 5 individuals/ml at a stocking density of 20 larvae/l. Four different feeding frequencies (twice a day, 3x, 4x and 5x a day) were compared. Catfish larvae provided with zooplankton at a feeding frequency of four times a day showed 152.8 mg final weight, 18.91±0.38 mg daily weight gain, 27.2±0.1%/day SGR and 95.33±4.6% survival rate. The result was significantly higher (p<0.05) compared to the other treatments (feeding frequencies). This experiment clearly indicated that zooplankton multiplied in ponds can effectively be used as source of live food and result in better performed C. gariepinus larvae when provided at a feeding frequency of four times a day.
Keywords/phrases: Cladocera, Copepoda, Diversity, Fertilizer, Live food, Multiplication pond, Rotifera