Finfish Breeding and Hatchery Management

Unit 3 - Breeding of major carps

3.6. Induced breeding of Indian major carps

• Breeding of fish with pituitary gland (hypophysis) extract is termed as Hypophysation
• The credit for developing the technique of hypophysation in the world goes to the Brazilians, while the pioneers of hypophysation of Indian major carps are H.L.Chaudhary and K.H.Alikunhi.
• Induced breeding refers to inducing fish to release gametes through the application of pituitary extract or hormones or chemicals.

Identification of sex of brooders

• Identification of sex is a prerequisite to induced spawning of the fish.
• Fish is sexually dimorphic and sexual dimorphism is exhibited primarily by gonads and their ducts and this involves killing of fish.
• Alternatively, the sex is identified based on certain morphological/external characteristics which include size, length, weight, colouration, fin characteristics, modification in the head in the form of nuptial dress, genital opening, width of mouth, etc.
• Carps are sexually dimorphic i.e. mature male and female are morphologically different.
• Some of the external morphological characters which are developed during breeding season could be used to identify sex in major carps which mature during their 2^nd or 3^rd year.
  

Characteristics	Male	Female
1. Scale, Operculum and pectoral fins	Rough to touch, particularly the dorsal surface of pectoral	Pectoral smooth to slippery
2. Abdomen	Round and firm	Swollen and soft
3. Genital opening swollen	Elongated slit, white in colour, not swollen	Round and pink
4. When pressure applied on abdomen opening	milky white fluid oozes through genital opening	a few ova may ooze through genital
5. Shape of body and size	Body linear, swollen	stouter, slightly larger

Male (top) and female (bottom) catla brooders