Tank Size:

A pair of keyholes can be kept in a tank of 20 gallons. A group or 6 or more is more advisable due to their social nature, meaning a 55 gallon tank is better off. These fish can get a chunky 4-6 inches long. Due to their chunky body some people refer to them as "the biggest 4 inch fish you've ever seen"

Feeding:

Readily accept anything you throw in the tank.

Tank Mates:

These are very timid, shy cichlids, and should be kept with other less boisterous cichlid species. I've kept mine successfully with bolivian rams, angelfish, and rainbow cichlids. They will need dither fish to come out and about comfortably, so smaller and medium sized tetra species are nice to have. Rummynoses, red eyes, bleeding hearts, just to name a few.

Sexing:

Males are said to have longer trailing fins than females.

Decor:

Should be kept with plenty of driftwood and plants, floating and rooted.

Water Perimeters:

Soft, acidic water is advised, though they'll live comfortably almost anywhere. Temperature should be 74-80F.

Other:

Some of the most timid cichlids I've owned, they took 2 months to really warm up for me. They've got a lot of personality, and have some gorgeous coloration. A keyhole will look better in a tank with lighter colored decorations and substrate, showing off a nice creamy white look. Mine have a more dark brown color to them due to the black sand and darkly colored pieces of wood.