Cichlids
A family that runs from an inch to well over a foot, many of them from the African rift lakes. Plenty are mouthbrooders: the eggs are carried in the mouth.
Overview
Cichlids are not one fish. They are a family of well over a thousand species in East Africa alone, and the differences between them are larger than the differences between most families of aquarium fish. A shell dwelling Tanganyikan an inch long and an eighteen inch oscar are both cichlids.
That is the practical point. Buying a cichlid means buying a species, because the tank size, the water chemistry, the diet and the list of animals it can live with are all set by which one it is, and getting that wrong is the usual reason a cichlid tank turns into one fish.
Temperament
Bright, watchful and territorial. Cichlids notice things. They rearrange substrate, they investigate a hand in the tank, and they hold a patch of ground against anything that enters it, especially while breeding.
Parental care is the family trait. Depending on species a pair guards a nest, or a parent carries the eggs and then the fry in its mouth, which is why cichlid tanks produce surviving young where other tanks produce a spawn and nothing else. Aggression is usually about territory and breeding rather than hunger, and it goes up sharply when either is in play.
Care and grooming
Diet is by species and covers most of the range: filamentous algae for the grazers, invertebrates for the mid sized fish, whole prey for the predators. Feeding a herbivore a protein heavy food causes real digestive problems, so the food follows the species rather than the shelf label.
Water is the same story. Rift lake species want hard, alkaline water, and South American species usually want it softer and more acidic. Across the family, 6.0 to 8.5 covers it and no single tank covers all of it.
Living and exercise
Thirty gallons is a starting point for the smaller species and nothing like enough for the larger ones. Rock work, caves and clear sightline breaks matter more than open swimming space, because a fish that cannot see a rival is not defending ground against it.
Stocking is worked out species by species. Some are kept as a pair, some in a crowded group that spreads aggression thin, and some alone. The mixed community of assorted cichlids that a shop tank suggests is the arrangement that most often ends badly.
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