In one of my previous articles, I wrote about the importance of seed in successful catfish farming. I will like to introduce my catfish fingerlings/juvenile supplier, Bunmi Alhade of Mosunmola Farms. In this article, she explains the process used in her hatchery to produce the best of breeds for customers who are in need of quality seeds.
Gone are the days when the African catfish fingerlings are captured from the wild. Aquaculture has gone beyond that and its associated problems like limited quantity, diseases afflicted stock, and stunted growth amongst others. These days the fingerlings are produced artificially in the hatchery, welcome to Mosunmola farms.
Breeding stock selection is a careful, planned and orchestrated process that is of great importance to the final outcome and output of the hatchery. Getting brood stock is not an easy process in Nigeria because so many brood stock farms tend to claim they imported their stocks as fingerlings from either Egypt or the Netherlands, and this might not be true. To get a good stock (with background information), one might need to travel as far as the Netherlands (Europe) or as near as Ijebu (South West, Nigeria).
The whole process of catfish breeding starts with identification of sexes and age of broodstock to be used. The average age for any breeding stock should be between 2-3 years to get healthy and good performing fingerlings. The male and female of the African catfish are similar in build yet different. The male has a distinct sexual papilla, elongated and located just behind the anus while the female catfish genital is swollen and has an opening.
To select the stock to be used for breeding, one needs to check for their sexual readiness. The viability of the African catfish is dependent on the brood stock health and management. For the male catfish, the sexual papilla is usually red at the tip for sexually ready males. While for the females, the genital opening will be swollen and red. A simple gentle push on the belly of the female fish should release ripe eggs, indicating its viability. Another thing that tends to give the female away is the swollen belly full of eggs, and viewing the fish from above, one would see that it is gravid and ready.
The next step is to weigh the female fish in order to have an idea of the approximate quantity of eggs it may have and also to determine the measurement of the synthetic hormone, which induces spawning (e.g. Ovaprim, Ovulin), to be administered. From experience and research, the weight of eggs in any gravid females is about 7-15 percent of its total body weight. This means if a gravid female weighed 2.5kg (that’s the least weight –size used at Mosunmola farms), the expected eggs that can be retrieved from its body ranges between 175g and 375g. Each female is weighed individually and the average weight is divided by 2, the resultant is measured in a percentage that gives the quantity (ml) of the synthetic hormone to be administered. To inject the females, care has to be taken not to inject on the lateral line of the body but on the flesh, and the needle needs to be injected at about 45 degrees to the body for better circulation. After the injection administration, the females are separated and kept in a comfortable environment to calm them and effect the administered medication. They are conditioned this way for the next 10 hours; say we inject about 9pm this night, the females would be ready for spawning around 6-7am the next morning. Mosunmola farms uses a ratio of 2:1; that is 2 females to 1 male, and the average weight of the brood stock is usually 3kg, with the males weighing nearly 4kg most times.
In the course of conditioning the females, the hatchery needs to be prepared for action. The incubating tanks need to be washed and sanitized to prevent infections. The hatching nets need to be soaked in saline to rid it of dead eggs and microscopic organisms that might affect the spread eggs. Above all, good quality water should be made available to promote the effectiveness of the hatching process. There are so many hatching management systems that can be used, but Mosunmola Farms uses a re-circulatory system; hence, there is need to make sure the pumps are in good working conditions.
Nearing the 10 hours induction period, the milt sacs are removed from the males (unfortunately they have to be killed for easy removal of the milt sac). Once killed, a sanitized razor blade is used to cut open the belly and the milts sacs are carefully removed and wrapped in a soft tissue. To strip the females of their eggs, the belly needs to be wiped clean by a soft tissue or cloth. Care needs to be taken so that the fish is calm by using a moist clean cloth to cover its head; also, the body needs to be angled in such a way that, in the process of stripping, the eggs are directed to the collecting bowl so as not to waste them. A gentle press on the belly should have the eggs spraying out. Once collected, open up the milt sacs and spread the sperm on to the eggs, add saline solution, mix gently, add just enough water and spread immediately on the hatching nets. The time between the opening of the sacs and spreading of the eggs should be as minimal as possible because most of the eggs on contact with the sperm get fertilized immediately and can get stuck to the bowl leading to wasting of viable eggs.
After spreading the eggs on the hatching nets, turn off the lights and ensure that the temperature in the hatchery is at the right degree (26-30 degrees). Wait 30-36 hours before removing the hatching nets; by this time the hatched eggs would have found their ways to the bottom of the tanks while the unhatched ones will be stuck to the net. Carefully remove the nets and wash immediately as the unhatched eggs can develop fungi which can affect the hatched eggs if care is not taken.
Looking down into the tanks, the hatched eggs (now frys) would be distinctively dark, with some frys still attached to their yolks when they collate, but indistinctive when they swim up in the first couple of days.
The whole process is exciting but extreme care has to be taken each step of the way. The African Catfish hatchery can be likened to an operating theater in the hospital.
Bunmi Alhade is an African catfish hatchery operator and CFO of Mosunmola Farms Nig. Ltd. She has her first degree in accounting and has a MBA. She has diploma certificates in aquaculture in practice and broodstock care and management. Mosunmola Farms has been in existence since 2005 and became fully operational in 2010.