LHRHa and pimozide-induced breeding in the catfish, Clarias macrocephalus (Gunther).

Abstract

Clarias macrocephalus is endemaic yet dwinding freshwater foodfish in the Philippines. Induced breeding protocol was developed after a series of studies which determined the appropriate egg size, proper time of stripping females, effective dose combination of luteinizing hormone-releasing hormone analogue (LHRHa) and pimozide (PIM), and their effects on egg quality. Based on its similar osmotic pressure with catfish plasma, eggs were fixed in 1% phosphate-bufferedd formalin. Catfish eggs with a mean diameter of 1.40 - 1.60 mm were responsive to hormonal treatment and increased to 1.50 - 1.70 mm at ovulation. Oocyte maturation, indicated by eggs in the germinal vesicle breadown (GVBD) stage, was observed at least 13 h pst-injection, followed by ovulation 4 h thereafter. Techniques developed in these studies showed a simsle, convenient, and effective way to induce spawning of C. macrocephalus. A simultaneous injetion of 0.05 ųg LHRHa + 1 ųg PIM/g BW at 1800 - 1900 h, followed by stripping at 16 - 20 h post-injection has consistently resulted in 100% ovulation, high fertilization and hatching rates.