Finfish Breeding and Hatchery Management

3.5.1. Broodstock management practice in Karnataka State

Unit 3 - Breeding of major carps

3.5.1. Broodstock management practice

Proper brood fish management forms the key to successful spawning. The number and quality of eggs produced are significantly affected by the conditions under which the brood-stock is maintained.

• The quality of brood-stock diet, feeding regime, the quality of brood-stock and water management are the principal factors that influence the condition of the broodstock.
• Most seed farms raise broodstock in their own farm (there are instances of inbreeding depression, as reported by Eknath and Doyle (1985) and maintain them in ponds at a density of 1,000-2,500 kg/ha.
• The earthen brood-stock ponds vary in area from 0.2 to 1.0 ha, with depth ranging from 1 to 2 m.
• The farms use water from perennial reservoirs.
• The number of brood fish ponds varies with hatchery requirement.
• The main basic steps in the preparation of broodstock ponds are : control of aquatic weeds, which in done manually; eradication of unwanted fish by applying mahua oilcake at 2,000-2,500 kg/ha and pond liming at 100-200 kg/ha depending on the pH of soil and water.
• This is followed by fertilizing the pond with cattle dung, at 15,000-20,000 kg/ha/yr or poultry manure at 5,000-10,000 kg/ha/yr to enhance heterotrophic food production.
• In addition, 200-400 kg/ha/yr NPK mixture is applied in split doses at fortnightly or monthly intervals.
• The initial dose of organic manure is reduced by half if mahua oil cake is used as piscicide.
• After stocking the pond with carps that are one-year-old or more, they are fed with a conventional feed containing a mixture of groundnut oil cake and rice bran (1:1 or 1:2 ratio) at 1-2% b. w., once daily.
• To ensure better and timely development of gonads, fish breeders use a special broodstock diet (protein : 25-30%) prepared using locally available cheap ingredients.
• This diet is nutritionally superior, advances maturation and spawning by one or two months and results in increased fecundity and better seed quality.

Ingredients	%
Rice bran	25
Groundnut oil cake	25
Fish meal	10
Maize	10
Broken rice	10
Horse gram	10
Blackgram	10

• This diet is given at 2% b.w. daily, starting in December.
• At some farms about a third of the broodstock will be injected with a low dose of HCG at 6-7 mg/kg body weight every 20 days, starting from mid-February for advancing maturation so as to induce spawning by the end of May.
• At some seed farms, a few vitamin E tablets are mixed, in addition to a small quantity of commercially available vitamin and mineral mix, in the diet to facilitate gonad development.
• Algal blooms and oxygen depletion are the most common problems encountered in broodstock ponds. These can be overcome by frequent water exchange.
• Although no major diseases occur in these ponds, infestation by Lernaea and Argulus on catla are common and are controlled by manual removal of adult specimens, followed by a dip treatment in a mild solution of potassium permanganate.