Inducing oocyte maturation, ovulation and spawning in the African catfish,Heterobranchus longifilisValenciennes (Pisces: Clariidae), using frog pituitary extract

摘要

Abstract.Oocyte maturation, ovulation and spawning were successfully achieved in the African catfish,Heterobranchus longifilisValenciennes, using frog pituitary extract. During artificial spawning, oocyte maturation and ovulation were induced at a dosage of 7mg per kg of individual fish weight. Latency period varied from 7 h at 29°C to 11 h at 25°C. Dead eggs became opaque between 8 and 10h after fertilization while embryogenesis was found to be temperature dependent. Mean hatching and larval deformity rates were 63·08± 7·56 and 8·08± 1·93 respectively. During induced natural spawning, the extract was applied at a dosage of 35 mg per kg of female fish weight. Spawning occurred between 10 and 11 h after hypophysation. Mean hatching and larval deformity rates were 41·38± 8·48 and 10·00± 2·00