MANAGEMENT OF BROODSTOCK
Brooders require extremely good water quality and proper feed to attain maturity in captive condition.
Brooders are fed twice daily with fish meal based feed containing 30-35% protein @ 3-5% of the body weight.
Water quality in brooder tanks should be maintained at optimum level by exchanging 20-30% water at fortnightly intervals.
BROODER SELECTION
Magur usually breeds during June to August.
When the fish attains 100-150 g size, they are considered ideal for induced breeding.
Male has elongated and pointed genital papilla near anus.
Fully matured female has bulgy abdomen and round button shaped genital papilla. Once the vent region is reddish in colour, we can understand the fish is ready to spawn.
Female maturity stages can be examined by gently inserting the soft-flexible catheter into the vent. The female is suitable for breeding when egg size is 1.2 to 1.4 mm.
FERTILIZATION PROCESS
Add the sperm suspension over the eggs.
Gently spread the sperm and egg with the bird feather for 2-3 minutes to mix thoroughly.
Add little quantity of freshwater water in the egg and sperm mix to activate sperm for fertilization process. Uniformly, mix the egg and sperm for effective fertilization.
Gently wash the eggs repeatedly (2-3 times) to remove any bloodstains, tissue particles and excess milt, which may affect the fertilization and hatching rate.
Gently spread the sperm and egg with the bird feather for 2-3 minutes to mix thoroughly.
Add little quantity of freshwater water in the egg and sperm mix to activate sperm for fertilization process. Uniformly, mix the egg and sperm for effective fertilization.
Gently wash the eggs repeatedly (2-3 times) to remove any bloodstains, tissue particles and excess milt, which may affect the fertilization and hatching rate.
INDUCED BREEDING
Synthetic hormones such as Ovaprim/Ovatide/WOVA-FH/Gonopro are widely used as inducing agent for magur.
Most of the synthetic hormones contain Gonadotropin Releasing Hormone (GnRH) and a neurotransmitter inhibitor. The GnRH induces the pituitary gland to release the Gonadotropin, which is the major maturational hormone; meanwhile the neurotransmitter inhibitor serves to remove other inhibition of GnRH release.
For magur, the optimum dosage of synthetic hormones is 1-1.5 ml/kg body weight
Most of the synthetic hormones contain Gonadotropin Releasing Hormone (GnRH) and a neurotransmitter inhibitor. The GnRH induces the pituitary gland to release the Gonadotropin, which is the major maturational hormone; meanwhile the neurotransmitter inhibitor serves to remove other inhibition of GnRH release.
For magur, the optimum dosage of synthetic hormones is 1-1.5 ml/kg body weight
PREPARATION OF SPERM SUSPENSION
The male fishes do not respond to stripping, so they have to be sacrificed for collection of testis.
They will anaesthetized with Chloroform solution.
The scissors has to be inserted from the vent region and the abdomen should be cut open with upward movement to avoid damage the internal organs. If the internal organs are damaged while cutting open, it will affect the sperm quality.
The good quality testis look like white creamy colour.
The bi-lobed testis along with the seminal vesicles should be carefully removed from the abdomen.
Wipe it with a tissue paper to avoid the contact of abdominal fluids.
Then the testis should be put in the pestle & mortar, add few ml of normal saline and macerate nicely to prepare the suspension.
Sperm suspension from 1 Male can be used to fertilize 2-3 Female.
They will anaesthetized with Chloroform solution.
The scissors has to be inserted from the vent region and the abdomen should be cut open with upward movement to avoid damage the internal organs. If the internal organs are damaged while cutting open, it will affect the sperm quality.
The good quality testis look like white creamy colour.
The bi-lobed testis along with the seminal vesicles should be carefully removed from the abdomen.
Wipe it with a tissue paper to avoid the contact of abdominal fluids.
Then the testis should be put in the pestle & mortar, add few ml of normal saline and macerate nicely to prepare the suspension.
Sperm suspension from 1 Male can be used to fertilize 2-3 Female.
STRIPPING OF EGGS
Female fishes stripped after 17 hours of injection to get ovulated eggs.
Gently press from the vent region and strip out the eggs in a plastic tray.
Then slowly strip out all the eggs from the abdomen.
Stop egg stripping, if the blood comes with egg.
The brownish-green colour eggs are good quality. The white coloured and blood-contaminated eggs should be discarded immediately.
Gently press from the vent region and strip out the eggs in a plastic tray.
Then slowly strip out all the eggs from the abdomen.
Stop egg stripping, if the blood comes with egg.
The brownish-green colour eggs are good quality. The white coloured and blood-contaminated eggs should be discarded immediately.
HATCHERY PROCESS
Once the fertilization process is over, the eggs should be incubated in the flow through hatchery for hatching.
A minimal flow through hatchery consists of a series of plastic tubs of 30 cm diameter and 15 cm height.
One tub can optimally accommodate 1000 to 1500 eggs. Each plastic tub has the provision of an outlet at a height of about 4-5 cm.
Magur eggs are demersal and sticky in nature and they are settled in the bottom of the tub.
The eggs are uniformly distributed in the incubation tubs and feeble water flow is provided to maintain optimum oxygen level.
The fertilized eggs hatch out within 24-27 hours from the time of fertilization.
The newly hatched larvae measures about 4-6 mm in length and 2-3 mg in weight
They carry the yolk sac, which gets absorbed at the end of 3rd day.
TAKEN FROM CIFA ICAR
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