Remarks: Calvus are best maintained as a single pair, but can be maintained in groups if in large enough aquaria. It's not particularly territorial and can make a good addition to a community of Tanganyikan species, but shouldn’t be kept alongside anything small enough to be considered food. It is not recommended as a companion for Tropheus or any others species requiring a low protein diet. They grow very slowly with some taking years to reach maturity.    In the wild, calvus are ambush predators that wait in crevices between rocks until prey comes by. Once it does, their mouth juts out to nearly the size of the tallest part of their body in one fast motion, engulfing their prey. These crevices are also where these fish spawn with both parents guarding the eggs and fry.   Black calvus are one of the most popular among calvus and compressiceps. It is easy to see why as upon maturity, they have inky black bodies and fins with white dots and vertical stripes. Sometimes they also gain blue accents to the tips of their fins making for a stunning fish. The Congo black calvus is said to have richest black coloration of all black calvus localities.