Catfish Production: Fertilization and Incubation of fertilized eggs
Catfish Production
Today we will be discussing catfish production. I will only share with you artificial reproduction in this post and practice is very effective in the production of catfish. Before the production of catfish, the following are to be ready:
- Female brood-stock
- Male brood-stock
- Ovaprim
- Saline
- Mesh net
Female brood-stock
Matured female fish are selected according to the following criteria:
A well-distended, swollen abdomen, sometimes reddish or rose-coloured genital papilla from which ripe eggs can be obtained by slightly pressing the abdomen towards the genital papilla.
Also Read: Cannibalism in Catfish and How to Reduce
Male brood-stock
Mostly males that above 1k can be used in fish production, ideally male fish should be larger than 500 grams and not less than 71/2 months.
Ovaprim
Is the hormone used on the farm and is administered at 0.5m per 1 kilogram of fish body weight. This is the most common hormone used by fish farmers in the Southern region.
Saline
This is prepared by mixing 9 grams of NaCl with 1 litre of boiled water or prepared. It is also sold in the market
Mesh net
This is made up of plastic pipe and a net (size 1mm).
Administration of Hormone
The most common method of administering the hormone is by intra-muscular injection into the dorsal muscle. The females are injected in the evening and are kept (separated from the males) in the holding facility.
Note: Cover the head of the breeder with a towel to keep it quiet during the injection. In general most fish keep still if their eyes are covered and the holding facility in which they are separated can be a simple plastic bucket, vat, or a half oil drum e.t.c for easy cash in the morning to avoid spoilage of eggs.
The time between injection and stripping depends on the water temperature.
The time it takes an egg to ovulate following temperature is presented below:
| WATER TEMPERATURE | TIME BETWEEN INJECTIONS AND STRIPPING (HOURS) |
| 20 | 21 |
| 21 | 18 |
| 22 | 15.5 |
| 23 | 13.5 |
| 24 | 12 |
| 25 | 11 |
| 26 | 10 |
| 27 | 9 |
| 28 | 8 |
| 29 | 7.5 |
Extraction of Sperm
The milt is taken from a male spawner and diluted with a physiological salt solution (9g of kitchen salt (NaCl) dissolved in 1 litre of boiled water) about half an hour before the females are stripped.
Stripping
Stripping of the female spawners is carried out by gently pressing their abdomen with a thumb from the pectoral fin towards the genital papilla.
Fertilization process of stripped Eggs
The sperm is added to the stripped eggs and is mixed with the eggs by gently shaking the bowl they become fertilized and an equal volume of water is added to the eggs to enable the damaged eggs to flow on the water then we decant.
Note: Eggs must be stirred continuously until they are placed in the hatching tanks reason is that the eggs become sticky and without stirring will stick together into one clump. About 60 seconds after fertilization has taken place the sperm lost its activities; the fertilized eggs are then ready for incubation.
Incubation of fertilized eggs
The eggs are spread out on a screen (mesh size 1mm) which is placed in the hatchery and this process is called Casting.
This method works well as the hatched fish will pass through the screen leaving the dead eggs and shells on the screen, the screen is removed from the basin separating the hatched fish and dead eggs
A time interval of incubation concerning water temperature:
| WATER TEMPERATURE IN CELSIUS | TIME INTERVAL OF INCUBATION (HOURS) |
| 20 | 57 |
| 21 | 46 |
| 22 | 38 |
| 23 | 33 |
| 24 | 29 |
| 25 | 27 |
| 26 | 25 |
| 27 | 23 |
| 28 | 22 |
| 29 | 21 |
| 30 | 20 |
