The Rainbow Cichlid Archocentrus multispinosus (previouslyHerotilapia multispinosa) is said to be the smallest of the Central American Cichlids. While it can reach just over 6 1/2 inches (17 cm) in the wild, they are significantly smaller in the aquarium and generally only reach a length of about 3 inches (7 cm).
They are personable fish and have been a long time inhabitant in the aquarium hobby. Some of their most notable and desired characteristics are their eponymous 'rainbow' coloring, their peaceful nature, and their compact and manageable size. Interestingly, their color is subject to a wide breadth of variability and will change significantly depending on its mood or if it is spawning. They normally present a brilliantly colored body in gold to orange with a broken black horizontal bar running the length of their body. They also display bright accents with orange on the eyes and on most of the fins, along with some beautiful blue hues on their lower body and fins and on the fin tips.
The colorful Rainbow Cichlid is a great addition to a community aquarium, and, due to its relatively small size, can be kept in a fairly small tank, unlike many other cichlids. Being peaceful it can be kept with regular tropical fish, much like Discus and German Rams. It can also make a very attractive show specimen in a species tank.
These are hardy fish and very easy to care for, and they are also not difficult to breed. They do require very clean water, however, so it is recommended to change their water regularly. A fine gravel substrate with rocks and pieces of driftwood for hiding places will make this dwarf cichlid feel right at home. They will also enjoy a heavily planted aquarium and will not generally disturb the plants. If you are going to have plants though, it's best to make sure they are hardy and and well rooted.
The Rainbow Cichlids, unlike other Central American cichlids, have tricuspid teeth. These teeth allow them to feed on the filamentous algae which makes up a good part of their diet in the wild. This does not pose any real dietary restrictions in the aquarium though, because they are not overly picky eaters. Their teeth had gained them their own monotypic genus under the name of Herotilapia with this fish being the only species in this genus. But more recently it was moved into the Archocentrus as one of three species.
The Rainbow Cichlid is a small colorful fish with a stocky oval body and pointed dorsal and anal fins. It is thought to be the smallest of the Central American Cichlids. In the wild they can attain lengths between about 2 1/2 - 6 1/2 inches ((7 - 17 cm), and the males tend to be a bit longer than the females. In the aquarium however, it matures at 3 inches (7 cm) and rarely grows much larger than that. They have a lifespan of 7 - 9 years with proper care.
The body is a golden to orange color and has an irregular black horizontal bar that runs from behind eye on the gill cover back to the tail fin. The eyes are orange and they have orange in most of the fins. The exceptions are the pelvic fins which are bright blue and the anal fins which are a mix of the two colors, with more blue towards the front and the last 1/3 being all orange. Their dorsal fin is orange with this same blue at the tips.
Unlike other Central American Cichlids, these fish have specialized teeth called tricuspid teeth. These are three pointed teeth that allow them to feed on the filamentous algae that makes up a large amount of natural their diet.
All cichlids share a common feature that some saltwater fish such as wrasses and parrotfish have. That is a well-developed pharyngeal set of teeth located in the throat, along with their regular teeth. Cichlids have spiny rays in the back parts of the anal, dorsal, pectoral, and pelvic fins to help discourage predators. The front part of these fins are soft and perfect for precise positions and effortless movements in the water as opposed to fast swimming.
Cichlids have one nostril on each side while other fish have 2 sets. To sense "smells" in the water, they suck water in and expel the water right back out after being "sampled" for a short or longer time, depending on how much the cichlid needs to "smell" the water. This feature is shared by saltwater damselfish and cichlids are thought to be closely related.
The Rainbow Cichlid is an omnivore and is a ready and eager eater. They will eat prepared foods including tubifex, freeze-dried bloodworms, ocean plankton, and floating food sticks. Feed a vegetable based flake as well. Feed twice a day in smaller amounts as this will keep the water quality higher over a longer time. Some suggest that a one day a week fast is also beneficial. All fish benefit from vitamins and supplements added to their foods.
A pair can be put in a 20 gallon tank, with 50 gallons suggested if kept with other fish. They prefer slow to moderate moving water along with good efficient filtration. Provide a fine gravel substrate with rocks, roots, and pieces of driftwood for hiding places. They will also enjoy a heavily planted aquarium and will not generally disturb the plants. If you are going to have plants it's best to make sure they are hardy and and well rooted. Do water changes of 20% weekly, depending on stocking numbers.