Finfish Breeding and Hatchery Management (2+1)

Identification and selection of brooders for injection

● Identification of sex of brooder is necessary to select sexual partners
● Fish is sexually dimorphic and some of the morphological/external characteristics like size, colouration, fin characteristics, genital opening, etc. which are prominent during season could be used
● Some of the external morphological characters which are developed during breeding season could be used to identify sex in major carps are as follows :

Characteristic	Male	Female
Scale, operculum and fins	Rough to touch, particularly the dorsal surface of pectoral	Pectoral smooth to touch  and  slippery
Abdomen	Round and firm	Swollen and soft
Genital opening	Elongated slit, white in colour, not swollen	Round and pink, swollen
When pressure applied on abdomen	Milky white fluid oozes through genital opening	A few ova may ooze through genital opening
Shape of body and size	Body linear, slightly smaller	Body stouter, slightly larger

Select medium-sized (1.5 – 5 kg) carp brooders aged between 2 and 6 years, for best results.