N. cylindricus is regarded by many as simply a leleupi without any color. I mention this not to lessen the intrigue this rock-dwelling lamprologine has to offer, but to emphasize just how closely these two species resemeble one another, both in appearance and behavior.
First and foremost, N. cylindricus is a rock-dwelling, substrate spawner. Both in the wild and in the tank, cylindricus stay very close to the rocks. Mine rarely ever stray more than a few inches from their caves, in contrast to the leleupi who are always out and about, but then use the caves to spawn. Cylindricus are always swimming in and out of my holey rock, and are usually found swimming on their sides or upside down, always hugging the rocks, which undoubtedly give them a sense of security. The adult male pictured to the left here, is usually found camped out in this little cave he's claimed.
I said that N. cylindricus is a substrate spawner, but it should really be called a cave spawner because this lamprologine will only lay its eggs in a cave. If no cave is provided, then it probably won't spawn. Spawning takes place in the female's cave. Eggs, numbering as many as 250, are laid on the walls of the cave, after which the male swims over them, depositing his milt. Larvae will hatch after 10 days or so and will begin to venture from the cave a week or so thereafter. The mother will protect the young for a few weeks and consequently, the parents may be left in the tank with the young.
In the wild, Neolamprologus cylindricus is a predator, feeding on zoobenthic organisms, aquatic insects, copepods, and whatever else they can find in and between the rocks. In the aquarium, however, they readily accept flake and pellet foods. A quality Spirulina-based flake food is highly recommended. Other recommended foods include white and black mosquito larvae, plankton, and the European Shrimp Mix. Cylindricus can be successfully kept in a planted tank as they won't touch even the tender shoots of new leaves. Anubias and Vallisneria species are both plant genera that do well in hard, alkaline water and don't require lots of light.
Males and females are equally colored, with males reaching maximum lengths of 5 inches, and females a bit smaller. These appearances will only become apparent after about a year and a half. Ideally, pair formation should be facilitated by growing up 8-10 juveniles. Pairs will form after about eighteen months, at which time they should be moved to other tanks. This is because they don't tolerate conspecifics and it's difficult to introduce a pair into a tank after they're adults. They can be quite nasty! They can also be kept singly, as they are solitary species. It's best not to keep them with the closely-related leleupi for reasons of aggression and hybridization.
There are several color morphs. All varieties have the ten dark, varetical bars from the lips to the peduncle. Cylindricus from the north, however, tend to have lighter stripes (brownish-black) while those populations from the south have broader and significantly darker stripes (all black). There is a gold-head morph, whose young display a yellowish color around the head, but this is lost as the fish matures and there is yet another variety that has blue on the tips of its fins and just under its eye. □