Altolamprologus calvus are first of all a wonderful Tanganyikan community fish. They seem to have a way of "turning" away aggressors by bending a little to expose their sharp scales that sort of stick out when the fish is bent. What makes it a good community fish is its non aggressive behavior toward tank mates. It eats mostly fry from other fish in the wild so it stays inconspicuous and conserves energy until it sees its pray and in an instant can dart almost faster than the eye can see. This skill does make it difficult to breed other fish with these "fry magnets" around but I'll get into that later. Any advice or recommendations that I give on breeding or well-being are things that have worked for me for a long time. These things may not work for everyone.
Nutrition - I do not recommend feeding things such as "feeders" that you can get from your local fish store. If you insist on feeding these, I recommend breeding guppies or something along that line. The reason that I do not recommend buying feeders from anywhere is the risk of contaminating your tank with parasites. There are theories that feeding live food will spark the eating of their own fry, however this is not something that I have experimented with. Once calvus are well adjusted they readily eat most flake foods such as brine shrimp flake. There are, however, many foods that they will benefit from. I feed brine shrimp flake at least once a day and usually frozen brine shrimp. I give them occasional blood worms, mysis shrimp, and I try to give them live brine shrimp about twice a month. I usually feed their fry frozen baby brine shrimp, however if you have the time to hatch your own that would be most beneficial.
Sexing - Sexing is extremely difficult to do in juvenile fishes. Your best bet is to buy at least 6 juveniles and trade off any extra males that you have (sexually mature males can become very aggressive toward each other). Try to get the largest one and several smaller ones. Adult calvus tend to have characteristics that can give a good hint as to the sex. Males get larger and usually have a higher forehead whereas the female stays a little more "bullet" shaped. To be absolutly sure you can vent them using a magnifying glass and a flash light. This is better to do with at least sub adults. What you are comparing is the size of the genital papila between the anus and the anal fin. The females will be larger than the male. If you have the same sexes the females genital papila will be larger than the anus, the males will be about the same size.
Water - In my opinion this is a very important topic, as I stated earlier this is what works for me. There are people that do very little to their water chemistry and have great success keeping these fish. I prefer to try to keep my water as close to the lake as possible. I do water partials of about 25% weekly and tanks full of fry I may even do 25% twice weekly. Altolamps. do not like big water changes , sudden fluctuations in PH or temperature but they do like very clean water. I like to keep a PH of around 8.8, temperature at around 76 degrees, and Carbonite hardness (KH) around 220 ppm. They are not tolerent to excesive levels of nitrate, therefor their tank should be kept free of wastes by good filtration and "vacuming" the gravel during partials. It is very easy to shock them so be patient when doing something to the water.
Breeding - In the wild Altolamps. will spawn using shells or tight openings in rockwork. The female will get out of reach of the male at this time to avoid injury. In captivity it is also important to remember that the female needs rerfuge at breeding time. Many use shells for their breeding set ups, this works great as does in the wild. In my experience I have tried to come up with a good method of extracting fry without disrupting the entire tank. I use pvc elbows capped on one end which should be large enough for the female but too small for the male to enter. These can easily be taken apart in a big bowl of water to retrieve your fry. It is also easy to see them against the white color when fry are free swimming. Altolamps. can be bred in pairs or in herems. I have had more success with herems with 1 male and around 4 females. I recommend a tank at least 29 gallons with hiding places for every female. I generally try to extract the fry before they leave home. This can be tricky since the length of time from wigglers to free swimmers can vary. (usually between 10 and 14 days). It is usually best to wait until the yolk sack is gone before removing them. If they leave home and venture into the tank they will most likely become food within a short time. I have even observed the mother eating them once they are on there own. Get ready for a long ride waiting for them to mature. It takes a lot of patience and hard work rearing calvus. It is not uncommon for it to take up to 6 months to get them to a 1 inch size. This is the reason that adults bring such a handsome price. It is my experience that males will be larger even at this age. When rearing fry it is very important to weed out the larger ones that could possibly eat the smaller ones, or bully them out of food. This takes at least 3 tanks or a large tank divided into different sections.
Conclusion - Is there a fish that is more interesting as the calvus? This "tribal" look that the calvus sports has brought it to the attention of both new cichlid keepers, and experienced alike. I cannot remember the last time that I have seen an adult calvus for sale in a fish store, nor do I remember the last time that I delivered an adult to a store that didn't sell before I left. Their growth be it slow reaps large rewards for those who are willing to invest their time and persistant attention. I highly recommend this awesome fish to add to almost any Tanganyika tank.