South America has at least 450 cichlid species but only 311 of them have been scientifically described. The latest complete scientific revision of this cichlid group was made during the early years of the 20th century. The South American cichlids have adapted to a wide range of environments and ecological niches. Most of the known South American cichlids are opportunistic carnivores or piscivores, but some species feed on mollusks, planktons or plant material. The smallest South American cichlid species are no larger than 3 centimeters while the largest can grow up to 60 centimeters.
One of the most famous South American cichlids among aquarists is Pterophyllum scalare, the freshwater Angelfish. Due to its Latin name, the Angelfish is also called Scalare. This South American cichlid lives in slow flowing streams and rivers where the water is soft and acidic. When you keep Angelfish the pH-value in the aquarium should be between 6.5 and 6.9 and the dH between 0.6 and 1.2. Poor water quality can easily make your Angelfish refrain from eating and good filtration and frequent water changes are therefore necessary. In comparison to many other tropical fish species kept by aquarist the Angelfish is a sturdy species when it comes to parasite attacks. It can however succumb to the common Ich (the Ichthyophthirius parasite) or Exophthalmia, especially when stressed by high levels of soluble waste, unsuitable water chemistry, a poorly decorated aquarium etcetera.
Another popular cichlid group that hails from South America is the Pike cichlids. Pike cichlids are not suitable for novice aquarists, but for the more experienced aquarist they are an interesting choice since Pike cichlids are active and fascinating predators. Their body is typically elongated and the mouth is broad and protruding. Pike cichlids will usually spend most of their time hiding behind rocks or sunken tree stems from which they can ambush unsuspecting prey. Pike cichlids belong to the genus Crenicichla and come in a wide range of sizes. The dwarf pike cichlids will not grow larger than 3 or 4 inches, while the largest Pike cichlids are 18-24 inches long. The medium sized Pike cichlids will typically stay around 6-10 inches. Dwarf Pike cichlids are popular among aquarists since they are easier to house than the larger Pike cichlids. Pike cichlids have gotten a quite bad reputation due to their aggressive behavior, but aggression is not a problem as long as you provide your Pike cichlid with an aquarium that is suitable for them. Pike cichlids like to rearrange aquarium décor, but they will usually refrain from uprooting plants. A fish that is smaller than the Pike cichlid is not suitable as tank mate since it will be considered prey.
Oscar cichlids are very popular among aquarist with larger aquariums. The Oscar cichlid – Astronotus ocellatus– lives in somewhat acidic waters in South America where wild Oscar cichlids are found in the River Amazon and in its tributaries in Paraguay and Brazil. You should keep the pH in the aquarium between 6.5 and 7.0 and the water should ideally be soft or just slightly hard. The recommended water temperature is 20-26 degrees C (70-80 degrees F). Oscar cichlids are intelligent and investigative and can grow bored in a barren aquarium. You should therefore include interesting things in the aquarium set up. Adding a new “toy” can perk up a bored Oscar fish.