Q. I am currently keeping several Haplochromis obliquidens from Lake Victoria. I would like to set up this species for propagation, but I have no information on how to do so. In particular, what should the male:female ratio be?
I am currently keeping their water conditions the same as in my Malawi cichlid fish aquariums: pH 8.2, total hardness 7 dKH (120.0 ppm), ammonia and nitrite 0.0 ppm and temperature 75 degrees Fahrenheit. The fish are very colorful and appear to be in excellent condition.
A. I must begin with the observation that the fish you’re maintaining are certainly not Haplochromis obliquidens. This species, a specialized grazer on the algae that grow on the stems of aquatic plants, has never been imported into either Europe or North America as an aquarium fish.
The freshwater fish usually marketed under the name Haplochromis obliquidens is an undescribed representative of the haplochromine genus Astatotilapia, known to researchers under the handy name of “thick-skin.” This species is widely distributed in planted shallow water habitats in both Kenya and Tanzania.
By virtue of its wide distribution, this species displays a fair degree of variation in the number and width of the dark vertical bars present on territorial or courting males. Males of the most commonly encountered aquarium population, which hails from the town of Migori in Kenya, sport four or five very wide lateral bars. This species remains fairly abundant despite the predatory Nile perch, and does not appear to be seriously endangered.
You appear to be caring well for your fish, but water conditions in Lake Victoria are quite different from those in Lakes Tanganyika and Malawi, so I suspect your fish would be a bit happier with a pH closer to 7.0 and the water hardness about half its present level. You are doing a superb job of managing the nitrogen cycle. If you can keep ammonia, nitrite and nitrate at present levels, breeding success with this — or any other cichlid from Lake Victoria — is virtually assured. The only other general husbandry suggestion I would offer you is to include a Spirulina-based flake food in the diet of your fish.
Like other haplochromine cichlid fish, Astatotilapia “thick-skin” is a maternal mouthbrooder with a markedly polygynous mating system. The association of males and females is restricted to the spawning act itself. The best way to minimize the risk of injury to sexually unreceptive females by overly enthusiastic males is to house these fish on a harem basis — a ratio of one male to as many females as one can find. If you have raised a group of fry to maturity, the sex ratio is probably close to 1:1.
Unless you are housing your fish in a very large aquarium (125 gallons or larger), it is unlikely that it will be big enough to accommodate more than a single territorial male. To ensure the survival of any other males, you should plan on moving them into an all-male aquarium as soon as they start showing obvious signs of wear and tear.
To maximize the genetic diversity of any fry that are produced, it is advisable to move the male from the breeding aquarium as soon as you see a receptive female and replace him with another male from the bachelor aquarium. This gives each male an opportunity to pass his genes on to the next generation.
The developmental period for this species is 14 days at 80 degrees Fahrenheit. Females are superb parents and can be counted on to carry their broods to full term without any need for human intervention.
This is a prolific species — a female around 2 inches (not including the tail) can easily release up to 80 fry. The newly released young measure about 12 millimeters total length, and have no trouble with either Artemia nauplii or finely powdered prepared fish food as a first meal. With frequent feeding and regular partial water changes, they grow rapidly.
Males can usually be recognized by their larger size, dusky ventrals and well-defined “egg spot” on the anal fin by eight weeks of age. Females usually begin their reproductive careers between 12 and 16 weeks of age.