Is it normal that Altolamprologus calvus grow very slowly?
I have had two Altolamprologus calvus for just under a year. They were about 4.5 to 5 cm long when I purchased them. Until now, they have hardly grown at all, their sizes are now approximately 5 to 5.5 cm. Is it normal that this species grows so slowly?
yes, this is normal! Altolamprologus indeed grow very slowly.
I have also heard that the females remain smaller than the males (as is the case with almost every Lake Tanganyika cichlid species), but they still should grow to about 10 cm, shouldn't they?
A 10 cm female would be a really capital specimen, although they may occasionally reach this size. However, 8 cm are more realistic.
Is it possible that this is because they are in an 80 cm aquarium right now?
This is not likely, good water hygiene provided. However, there is possibly another reason: There have been reports, especially about Altolamprologus, that young/growing fish release a pheromon that slows down the growth of other members of their species.
The smaller one of the two at the moment has a slightly concave belly. It behaves completely normal, actively swims through the aquarium when looking for food, eats completely normally, sometimes fights with the other one and shows the typical threatening behavior when doing so. He always gets enough when I feed, the bellies of both fish look pretty much the same after feeding. But on the next day, at the latest, the belly of the smaller one is considerably concave, whereas the other one has a "normal" belly. Do I need to worry?
It would at least be a good idea to examine a fresh (!) fish waste sample for possble parasites (most likely flagellates or worms) under a microscope, either to be able to exclude problems of that kind, or to be able to recognize and treat them.
Dr. Bodo Schnell