HCG and LHRH-A induced spawning in bighead carp Aristichthys nobilis Rich. reared in floating cages in Laguna de Bay

Abstract

Hormone-induction of spawning in bighead carp Aristichthys nobilis Rich. by single or double intraperitoneal injection with varying combined dosages of HCG and LHRH-A was conducted. Fish were spawned successfully following a single or double injection with 1800 to 2000 IU HCG in combination with 10, 15 or 20 µg HRLR-A per kg body weight. Fish injected with lower dosages of HGC at 1200 or 1500 IU/kg body weight plus 20 µg/kg LHRH-A did not differ significantly (P>0.05). Fish given a single injection ovulated after 12.0 ± 0.1 hours. No significant difference was found in the total number of eggs spawned per fish among the injection protocols (P>0.05). However, lower fertilization and hatching rates of eggs were observed in fish that spawned spontaneously in the tank as compared to those fish whose eggs were stripped and dry-fertilized (P<0.05).