Catfish farming is fast becoming a striving agribusiness with promise of great yield. It is however a wide venture and farmers can choose from several niches to invest in from hatchery to processing. A previous article discusses these niches, their requirements and potentials. The fast growth of this business in Nigeria births the need for good quality catfish seeds for stocking in grow-out ponds.
Several methods exist for the breeding or propagation of the African Catfish. These methods may be grouped into three categories: natural propagation; semi natural propagation and artificial propagation.
For natural propagation, males and females are placed together in a breeding area such as a small pond or an enclosure where they spawn naturally. For successful natural breeding of the African catfish, environmental manipulation such as the inflow of new water and a sudden rise of the pond water level to simulate inundation (flooding) as in the wild is required.
For semi-natural propagation, the female fish are injected with chemicals which trigger spawning. Males and females are then placed together in a specially prepared breeding area where spawning takes place. The fertilized eggs can then be collected and reared under improved conditions, either natural or artificial.
For artificial propagation, the females are given one or more injections of chemical which bring about final ripening of the eggs in the ovaries. As soon as the eggs are ripe, they are stripped from the females. Eggs are artificially fertilized with sperm obtained from the males and reared under controlled conditions.
The artificial method of propagation is discussed in the next part of this series.
This article focuses on the different kinds of chemicals that can be used to inject the female catfish for semi-artificial or artificial reproduction. The hormones or chemicals generally used are:
1. Pituitary gland of the African Catfish.
2. DOCA (Deoxycorticosterone Acetate.
3. Human Chorionic Gonadotropin (HCG).
4. Luteinizing Hormone-Releasing Hormone (LH-RH) and its analogues.
5. A combination of Gonadotropin Releasing Hormone analogue and the drug domperidone (a dopamine inhibitor).
Procedure for extraction and preparation of Pituitary gland (hyophysis).
Pituitary gland can be procured fresh from a donor fish of equal weight as the brood stock or from stores as Acetone dried carp pituitary. The procedure for extraction from a donor fish is as follows:
1. Kill the fish by cutting off the head.
2. Turn the head upside down on a table and remove the lower jaw of the fish.
3. Cut open the brain case from the upper jaw.
4. Remove the pituitary gland which is located before the brain and can be identified as a creamy white globe-like structure with a spatula.
5. Prepare 0.9% physiological salt or saline solution (9g of common salt to 1 liter of distilled water).
6. Grind the pituitary gland (fresh or dried) in a dry porcelain mortar and add 0.1ml of glycerin (for viscosity) followed by 1ml of the salt solution.
7. Remove tissue residues and centrifuge the solution. Allow the solution to settle for 5 minutes then suck up the clear solution with a syringe needle.
The most common commercially sold hormones used in artificial propagation of catfish are Ovaprim, Ovulin, and Ovatide. They compose mainly of the same thing (a combination of LHRH-A, and the drug domperidone) but have different dosage instructions.
HORMONE DOSAGE RATE
HORMONE DOSAGE RATE
Acetone dried Carp pituitary 4mg/kg body weight of fish
Fresh fish pituitary gland Pituitary gland of donor fish with equal weighT
Human Chorionic Gonadotropin 4µg/ kg body weight of fish
