Two nearly identical species with the exact same temperaments and care requirements, so they'll both have the same guide

Tank Size:

a 36" tank is advised for a full grown specimen.

Feeding:

Carnivores, provide a nice high protein diet. Will readily suck up and fry they find with their large mouths. They're specially built for sneaking up and raiding fry nests.

Tank Mates:

These fish are mild tempered, and defend rather than attack. They turn their bodies toward their attackers, and with their sharp, serrated scales, will cut up the mouths of their attackers. Attackers eventually learn not to mess with them. Go well in almost any tanganyikan tank, though should be kept with other carnivores. Keeping them with herbivores such as tropheus moorii and goby cichlid species can lead to food being mixed up and eventually bloated, sick fish. Keep in mind that due to their fry eating tendencies they should not be kept in tanks where you want fish to breed successfully. They should be kept alone or in a large group of 8+. Larger groups need at least a 6 foot tank.

Decor:

Lots of rocks. These fish are very shy rock dwellers. Though they tend to hide in the rocks, they are nomadic and will not claim a territory.

Sexing:

Not sexable.

Water Perimeters:

Temperature should be kept at 78F and pH should be 8.2-9. These fish are not tolerant of perimeter shifts or dirty water, and are not advised for beginners.

Other:

These fish grow slower than heck, you should not expect more than an inch of growth per year. They will eventually reach a good 6 inches long, though. It'll just take a long time, so keep this in mind. They also have a pretty long lifespan if properly cared for. They have plenty of colorations, such as gold, black, white, goldhead, etc.

The way to tell a calvus from a compressiceps is to look at the mouth. A calvus has an elongated face, whereas the compressiceps has an upturned snout.