The family Cichlidae can be broken down into two basic groups: New World cichlids and Old World cichlids. That is, cichlids endemic to the Americas and Africa, respectively. These two groups can be broken down further, as follows (with their general pH requirements in parentheses):
New World Cichlids
1. South America (ph 6.5-7.5)
-Pikes and peacock bass
-Oscars
-Geophagus species
-Apistogrammas
-Discus, angels, uaru, festivum
2. Central America (ph 7.0-8.5)
Old World Cichlids
1. West African river species (ph 6.5-7.5)
-Jewels
-Kribs
-Tilapia
2. Lake Tanganyika (ph 8.0-9.0)
-Lamprologus
-Tropheus
-Frontosa
3. Lake Malawi (ph 7.5-8.5)
-Mbuna
-Peacocks
-Nimbochromis/haplochromis
Determining aquarium compatibility between cichlids can be tricky and never guaranteed, but below is a summary of what generally holds true. The most important thing to remember about cichlids is that the vast majority of cichlids are at least moderately aggressive even when not breeding. Once two cichlids have paired up and begun their mating ritual, their aggressiveness increases dramatically.
The South American cichlids are a very diverse group. The giants are the Oscars, pikes and peacock basses. These fish are typically not aggressive, but all have clear piscivorous tendencies; they will quickly eat any tank mate small enough to fit into their mouths. Despite this, these fish are not highly aggressive, and will not fair well with more aggressive tank mates. Their food should have a high concentration of meat protein.
Most of the other S. American cichlids can more or less be considered semi-aggressive community fish. Although some geophagus species get large and aggressive, most are not excessively territorial and can be kept with smaller, more docile fish. The jurupari is a good example of this. The apistogrammas, discus, angels and uaru are also relatively non-aggressive and can be kept like the geophagus. With the exception of uaru, they are also good candidates for the planted aquarium.
Only a couple of S. American species Fintastic carries should be considered too aggressive to be kept with the above fish. These are green terrors and caquetaia kraussi. Both are usually mean and nasty, and would probably do best housed with cichlids from C. America. With the exception of the true predators, the S. American cichlids are omnivores, and should be offered a wide variety of foods, including a fair bit of vegetable matter.
Central American cichlids are, as a rule, highly territorial and predatory. Although some stay around six inches when full grown, such as the convict, salvinii and Jack Dempsey, most get closer to ten to fourteen inches. These are not suitable for smaller aquariums except when juvenile, and they typically grow very quickly when kept properly. It is usually impossible to house more than a single adult C. American cichlid in an aquarium unless the tank is very large. Being omnivores, these cichlids are easy to feed.
Lake Malawi cichlids are very diverse and should not be considered compatible across the board. Fintastic sells more mbuna than any other type of Malawi cichlid. These are the smaller(4-6”), algae eating fish of the lake. As such, they should be offered lots of algae-based foods. It is necessary to have a can of OSI Spirulina flake, HBH Spirulina pellet or Ocean Nutrition Cichlid Vegi flake to an mbuna sale. Examples of mbuna we sell are the auratus, kennyi, zebras, etc. Although often very aggressive, most mbuna can be successfully kept in communities, even in tanks as small as thirty gallons. In fact, it is best to slightly overcrowd them in order to distribute aggression among as many individuals as possible. Obviously, what this means for the aquarist is an increase in size and frequency of water changes. It is important to note that, although they are technically mbuna, yellow labs are best not mixed with other mbuna. They are not as rowdy, and usually get harassed/damaged. If you insist on mixing them in with more aggressive fish, try to give the labs a size advantage.
The haplochromines are a larger, predatory Malawi fish. Some of the haps Fintastic sell’s are the venustus, compressiceps, livingstoni, etc. Most of these fish reach eight to ten inches and need lots of swimming space. They are best fed an omnivore diet, with a leaning toward meat protein. Do not house these fish with mbuna unless they are clearly larger, and in a tank of at least 75 gallons. Peacocks, probably the most spectacular and expensive Malawi cichlids and should not be housed with mbuna under any conditions. They are simply not nearly aggressive enough. The only exception to this would be the yellow labs, for the reason given above. They typically grow no larger than four to five inches, and can be housed in tanks as small as thirty gallons. They are micropredators/omnivores, and will thrive on a mixture of frozen and dry foods.
With the exception of the frontosa, Lake Tanganyikan cichlids generally stay under six inches, are not insanely territorial, and do well in communities of other Tanganyikans. Such a community should be housed in at least a thirty gallon, but preferably larger. Do not mix these fish with any Malawi cichlids other than yellow labs and peacocks. Feed Tanganyikans a mixture of frozen and dry foods. Do note that tropheus species should absolutely not be fed bloodworms or brine shrimp.
West African cichlids are very similar to New World cichlids in most regards. Their water, feeding and housing requirements are very similar to those of the S. American cichlids, while their temperament typically is a little rougher. Depending on the species in question, these guys can usually be mixed in with cichlids from South and Central America with no problem.
As a final note, we would like to point out that, like marine reef fish, cichlids from the large African rift lakes are intolerant of large swings in water parameters and degradation in water quality. These fish need constant high pH and alkaline water conditions (buffers are a must). The South and Central American and African river cichlids, on the other hand, are accustomed to seasonal changes in water chemistry and can be difficult to upset.