An Overview of the Main Groups of Tropical Fish

CICHLIDS

All cichlids exhibit some form of parental care. In order to do this or to attract mates they must hold a territory. Other fish may be regarded as competitors, intruders or predators of young. It is for this reason that cichlids have the reputation of being fairly stroppy. In some cichlids, this behaviour is pronounced eg the Jack Dempsey and Oscar. In others it is less apparent eg Kribensis, Rams and Angels. The cichlids are a very large group with many types of behavior and varying requirements. Cichlids are best researched individually for this reason.

CATFISH

Most catfish are benthic ie they are substrate dwellers. As there is typically a lot of debris at this level (roots, rocks etc) catfish do not have scales, and instead are equipped with thick leathery skin or bony plates.

All true catfish have barbels around their mouth, which are highly sensitive taste organs, used in the search for food. Although catfish are often referred to as scavengers, they do not eat waste from other fish and require proper nutrition in the form of sinking tablet food, algae wafers etc. Hiding places are important for catfish, including the free swimming species. There are over 2000 species of catfish, and a lot can be determined about them by their mouthparts. Sucking cats typically rasp algae of rocks, driftwood etc, and algae makes up an important part of their diet. Plecostomus and Bristlenose Ancistrus are examples of these. Substrate sifters such as the Corydoras cats and Port Hoplos have specially adapted mouthpparts for this purpose. Some of the larger cats are predatory on other fish and typically have very large mouths eg the Shovel nosed cat.

CYPRINIFORMES

This group comprises the barbs, rasboras, danios, loaches, sharks and goldfish.

BARBS

Barbs are a schooling fish and are best in groups of six or more. With the exception of the Tiger Barb (which is a fin nipper), they are good community fish. Barbs require a close fitting lid to the aquarium as they are quite 'jumpy'. Most barbs are omnivorous and it is beneficial to add a vegetable supplement to their diet. Some common barbs include; cherry barbs, golden barbs and tin foil barbs.

DANIOS

Danios usually occupy the top level of the aquarium and their upturned mouths are suited to taking insects from the surface. They are fairly easy care and do well in a school of six or more. Zebra danios are a popular community fish.

RASBORAS

The Harlequin Rasbora is the most popular fish in this group as well as the larger Scissortail. They are surface dwellers like the danios and prefer to school.

SHARKS

The sharks, so called for there body shape, include the chinese algae eater, the rainbow and the red tailed black shark. These fish become quite stroppy to their tank mates once they approach maturity. The silver shark, a schooling fish is peaceful, although it grows fairly large and is not suited to small aquaria.

LOACHES

The clown loach is the most familiar example of this group of fishes. Loaches are typified by a two pronged spine beneath the eye which can become entangled in nets and puncture plastic bags.

The mouth is covered in barbels covered with taste receptors which help the fish to find their favoured food of insect larvae and worms. They will accept tablet and frozen food in the aquarium. Many loaches are partially scaled or have no scales at all. Some medications are not suitable to be used with these fish for this reason. Hiding places are important for loaches.

CYPRINODONTS

This group includes the livebearers and killifish.

Livebearers include guppies, mollies and platies. All are excellent community fish and are suitable for small aquariums due to their modest size. Water quality is particularly important and regular partial water changes are neccessary. Hard alkaline water is preferred and the addition of a small amount of salt, particularly for the mollies. Livebearers are prolific breeders and as the name suggests, the young are born live. Frozen and live foods are a beneficial addition to flake foods.

Killifish are an egglaying fish. Some killifish are referred to as 'annuals' in the wild as they live in ponds that evaporate in the dry season, and only their eggs are left to hatch when the rains arrive.

CHARACINS

Characins are a large group of fishes, the tetra being the most important. They are characterised by the Weberian apparatus (the linkage of bones between the swim bladder and the inner ear) that allows them to hear high frequency sounds.

Generally characins are schooling and live in clean, clear running water. Water quality and oxygen content is therefore very important. The piranha is included in this group, however most species are peaceful eg neon tetra, congo tetra. Other characins include Distochodus, pencilfish, anostomus and hatchet fish.

ANABANTOIDS

The gouramis are the most notable of this group which are typified by the ability to breath atmospheric air. This is achieved by way of a labyrinth organ, a sponge like structure in the head. This allows these fish to live in oxygen deficient waters. Siamese fighters, paradise fish and the African Ctenopomas also belong to this group. Many fish in this group construct a bubble nest to keep eggs at the surface, which is another adaptation to an oxygen poor environment. These fish are fairly easy care and most are suitable for community aquariums.

RAINBOWFISH

A small to medium sized group of fish that fit in well with most communities. A well planted aquarium of at least three feet is necessary as rainbows are very active.