OVARIAN DEVELOPMENT AND SERUM STEROID-HORMONE PROFILES IN HATCHERY-BRED FEMALE CATFISH CLARIAS-MACROCEPHALUS (GUNTHER) DURING AN ANNUAL REPRODUCTIVE-CYCLE

Ovarian development e.g. gonadosomatic index, oocyte diameter, fecundi ty, histology, and related steroid hormones e.g. testosterone (T), est radiol-17 beta (E-2), 17 alpha, 20 beta-dihydroxy-4-pregnen-3-one (DHP ), were examined in captive female catfish Clarias macrocephalus durin g an annual cycle to establish the optimum season for its artificial p ropagation. Results showed that captive C. macrocephalus had a group-s ynchronous pattern of ovarian development, as indicated by the presenc e of oocytes at all stages of development throughout the annual cycle. Mean gonadosomatic index (GSI; 11-13%), oocyte diameter (1.54-1.56 mm ), fecundity (80-110 eggs/g body weight), and serum T levels (36-37 ng /ml) were lowest in January-April, suggesting that it is not the optim um season to induce C. macrocephalus to spawn during these months. Ser um E-2 levels were lowest in January (7 ng/ml), and highest in Decembe r (20 ng/ml). Serum DHP levels were below detectable limits (< 0.02 ng /ml) throughout the year, supporting the observation that final matura tion and ovulation do not occur in this species under captive conditio ns. Changes in various reproductive parameters and steroid hormone lev els indicate that January-March, April-June, July-September and Octobe r-December correspond to the refractory, preparatory, spawning and pos t-spawning periods, respectively, of the annual cycle. The results of the present investigation can be used as a guide for the controlled br eeding and commercial aquaculture of C. macrocephalus in the Philippin es.