The last one week has been a rollercoaster sort of for me, I haven’t posted any article, although I have been interacting with some posts. It is mainly because my phone has issues; one of which is the blackout of a part of the screen, and also, the charging port has been shaky. Thus, charging my phone has been frustrating, because in the past two weeks, I have only been able to charge my phone full on two occasions. It’s mostly been between the range of 30%—45% .

I had said before in my article The First of Many that I am a student studying Aquaculture and Fisheries Management. I am in my penultimate year, and this is our Field Practical Training year wherein we indulge in hands-on training.

The highlight of my week was a group project which involved crossbreeding of Clarias garipienus (African mud catfish). The project was basically an experiment which involves breeding two parent broodstock from the same farm and two parent broodstock from different farms.

Due to the fact that clarias spp can’t spawn when in captivity, the female brooder has to be artificially induced to complete her egg development. After which the eggs are stripped out of her and fertilized with milt gotten from the male brooder which has to be sacrificed first.

The first step to artificial breeding of African mud catfish is selection of broodstock. Male and female brooders of desirable phenotypic traits are selected. The biggest from the stock of same age are selected, as it is believed that fish produced by the selected brooders have the tendency to grow big in the shortest time as their parents.

We arrived at the farm we are to buy the broodstocks needed for the experiment and the owner wasn’t around, just his wife, who isn’t exactly skilled at the job. So, it fell on us to harvest (catch fishes in tanks) and make our selection which involves checking for desirable traits and also checking if the broodstock is gravid and if the eggs carried by the female brooders are viable. I volunteered to harvest them from the tanks, and believe me, it wasn’t an easy task, neither was it a clean one.

Since I had volunteered, she started draining out water from the tank the fish were in. The tank couldn’t drain out completely and that made the harvesting more difficult, since you’ll have to catch the fish while it is swims around, and also, you can’t really see the fish, so you’re not sure which fish has the desirable character(s) you want. So, for me it became a sport, one of chance, and provided certain conditions are met at a particular time, the probability of catching a fish with desirable character(s) are high.

I was swimming with the fishes for over an hour, harvesting, and if the fish caught is desirable, I put it into a bowl and give it to my mates for further examination. We had gotten the three male brooders we needed as well as a female brooder. But we need to female brooders. I came out from the tank and checked all the female fish I had caught, but none ticked all the necessary boxes I wanted.

I told the owner's wife I was going back into the tank to check for more female brooders. But she said she had to leave soon to go pick up her daughter from school. My some of mates gave me a look and I could tell they were vexed. I suppose since we’ve been working for over an hour, they must be exhausted. One of them asked to me “Gift, you didn’t pick one of the female brooders because it wasn’t the size you wanted. Are you buying size?” I answered “I am concerned about the success of this experiment, and size of female brooder is one of the factors I can influence to ensure the success of this experiment…”.

I had learnt that in induced breeding of catfish, the size of the female brooder is proportional to hatchability rate. So, I went back into the tank and continued the sport. I caught several ones until we finally settled for the biggest female catch. Although, I had to be convinced about the viability of the eggs she was carrying.

After selection of brood stock, the next phase is inducing of the female brooder with artificial hormone so she can complete oogenesis. It usually takes 12hrs or more to start ovulation, depending on the dosage of hormone given to the fish.

When the female brooder starts ovulating, the eggs are stripped into a plastic bowl and saline water (with 0.9g sodium chloride) is added to keep it alive for as long as is necessary until the male is sacrificed for his sperm sac.

After adding the milt to the eggs in the bowl, it is gently stirred with a plastic spoon so as the eggs are not damaged. After stirring, the eggs are incubated in hatchery tanks for at least 24hrs depending on temperature of the water and the environment.

Conclusion

It's been days since we incubated, and although many of the eggs hatched, we lost the hatchlings due to our carelessness. Anyway, my group has agreed to re-do the experiment, and not repeat the same mistake again. Hopefully, it's a success this time around.

Thank you for reading ✍🏿🙏🏿💪🏿