Induced maturation and spawning of milkfish, Chanos chanos Forsskal, by hormone implantation

Abstract

The milkfish, Chanos chanos Forsskal, does not reach gonadal maturity easily in captivity. In an attempt to induce maturation, exogenous hormones, LHRH-A and 17α-methyl-testosterone, were implanted into adult milkfish either alone or in combination. The hormones were delivered using cholesterol pellets (LHRH-A) or silastic tubing sealed with elastomer (17α-methyl-testosterone). The fish were implanted three times at monthly intervals between March and May of 1985. The combination of LHRH-A and 17α-methyl-testosterone induced significantly more maturing fish (P < 0.05) than LHRH-A alone or sham controls; 88%, 38%, and 13%, respectively.

Fish with average egg diameters between 768 μm and 905 μm, spawned 48 h after hormone implantation. These results indicate that the maturation and spawning of milkfish in tanks can be induced and accelerated 1–2 months earlier than the beginning of the normal spawning season through hormone implantation.