Induced breeding of exotic carps (silver carp and grass carp)

First introduced into India in the year 1959 The silver carp and grass carp are native to China and hence are known as exotic carps First introduced into India in the year 1959 Both were successfully induced bred in 1963, through hypophysation The method of hypophysation of these species is similar to that of IMC However, there are a few minor differences – the dosage of pituitary is double compared to IMC and, unlike IMC, they do not spawn naturally after injection, in captivity. Figure: Silver carp Figure: Grass carp

Of the two methods of fertilization, the wet method is more successful The sex of brooder is identified based on the morphological characteristics such as fins, abdomen, genital opening, etc. The same critera that are used for IMC can also be used for silver carp and grass carp Although they can spawn naturally when fed on artificial diet, instead of aquatic plants, realization of spawn will be lower To facilitate better fertilization, the eggs need to be stripped by applying pressure on the abdomen and eggs fertilized by mixing with similarly stripped milt Of the two methods of fertilization, the wet method is more successful Figure: Male (top) and female (bottom) grass carp brooders

Fertilization of eggs :   After hormone injection, the male and female brooders are released separately in breeding hapas The female brooder is checked for ovulation at 3-4 hours interval After ovulation, the female is stripped and the eggs are collected on to a clean basin/tray, avoiding any contamination with faeces, mucus, blood, etc. Eggs are then mixed with milt stripped from more than one male (preferably 2-3 males) to ensure better fertilization as these fishes produce comparatively less milt The water-hardened developing eggs are transferred to incubators for hatching The method of hatching of eggs and hatching period are same as that of IMC