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Seven Families of Aquarium Fish

Learn about the seven families of aquarium fish.

By Mike Nolan

Page 3 of 3

The Loaches
Often confused with the catfish, these fish belong to the family Cobitidae. They are mostly from southeast Asia and India. Loaches tend to be longer and more rounded than the catfish, approaching a worm or eel shape in the extreme, such as the ever popular coolie loaches. They exhibit the same colors as the catfish, with additional brightness and oranges, resulting in some very beautiful fish, such as the clown loach.

Although not quite as hardy as the catfish, they will do very well in most waters, particularly if well fed. Many members of this group are secretive, coming out only to feed at night. Often, aquarists will go weeks at a time between "sightings." Don't let this last statement prevent you from trying some of these fishes. Their biggest drawing card is their antics. Clown loaches, for example, will sometimes roll over and play dead.

The Livebearers
The livebearers are best characterized by their name. They all give birth to live young that are miniature versions of their parents. Interestingly, in the aquarium literature of the 1930s, these fish were often divided into two groups: livebearers and egglayers.

These fish are members of the family Poeciliidae and come from southern North America, Central America and the Caribbean Islands. Many live near the coast, often in brackish waters. They tend to be small fish, on the order of a few inches in length, with the male often smaller and more colorful than the female. These fish have been bred in captivity for many generations, resulting in a wide variety of color strains with different kinds of finnage. There are also hybrids.

These fish do very well in the harder, more alkaline waters that come from the taps in most parts of this country. They appreciate, and some species require, the addition of a small amount of salt in their water. While they will accept any and all foods that are small enough for them to swallow, these fish are primarily carnivorous, feeding on insect larva in the wild. In fact, members of this family often play important roles in mosquito control programs. They will thrive much better if you give them a little "meat" in their diet. The popular mollies are an exception and do best with the addition of vegetable matter to the diet.

The outstanding feature of these fish is their production of live young. The fry are large and can eat within minutes of birth. They will reproduce in a community tank. However, the parents will quickly eat any young they can find. If you wish to save more than a few of the fry, steps need to be taken almost immediately after birth to separate the parents from the young.

The Cichlids
The members of the family Cichlidae are the notorious bad guys of the aquarium hobby. They have a reputation as bullies. Why then are they the most popular of fishes among advanced aquarists?

The cichlids are a very diversified family from Central and South America and tropical Africa, with even a few from the Southeast Asia and the Indian subcontinent. This is the one family that destroys my hypothesis that the maintenance requirements can be well established if you know what family a fish belongs to. This family includes fish with special water requirements on both ends of the scale. Almost all cichlids are less tolerant of laxity in the maintenance of good water quality than other tropicals. Cichlids include fish as gentle as the discus and angelfish and others that are self-propelled fish eaters (or as a friend said recently, a "swimming attitude problem").

Most cichlids have a classical fish shape. They tend to have very prominent fins and posses all of the colors of the rainbow. They come in subdued colors and in gaudy ones. They range in size from 1½ to 10 inches or more. Some will eat almost anything that can be thrown into the tank, whereas others have specialized feeding requirements.

Why are they popular? Quite simply because of their behavior. They are among the most intelligent of fishes. Many come to recognize their owner from other humans, and some know when feeding time is and will protest or remind you if you forget. They exhibit very elaborate spawning rituals and practice care and protection of their young in numerous ways. The observation of a pair of cichlids raising their young, feeding them and protecting them is among the most satisfying experiences in the hobby.

Don't let their reputation prevent you from investigating these fish. At the same time, do not buy a cichlid on impulse until you have had time to investigate its needs further and are prepared to provide suitable quarters.

The Labyrinth Fish
The labyrinth fishes are members of four closely related families. The majority of the readily available fish belong to the family Belontiidae. They are commonly known as the gouramis, the betta and their close relatives. All of these fish possess a means for breathing atmospheric air, called a labyrinth. Thus the name. To recognize these fish, look for specimens of 2 to 4 inches that are considerably "taller" than they are wide. They are brightly colored, with some of the smallest members (e.g., the dwarf gourami) possessing the best coloration. In some species, the females are less colorful than the males.

These fish prefer the top portion of the tank for their home. They do best in water that is a little warmer than the temperatures preferred by many of the other fish we commonly keep. Members of this family tend to feed from the surface and should therefore be provided with foods that float.

Although a few can get a little nasty, the majority are quite peaceful and can be kept with several of their own kind or with a couple each of several different kinds. Their tank should definitely contain some plants for shelter and to provide a feeling of security. The addition of floating plants will add greatly to the well being of the labyrinth fishes.

These fish exhibit a very interesting breeding behavior. They build a nest at the surface of the water. Sometimes bits of plant are incorporated or the nest is placed under leaves or other objects. The nest is constructed by the males with bubbles formed of air and saliva. Spawning occurs under the nest, and the eggs are placed in the nest by the male, who then guards and cares for the nest and eggs while they develop. This care is sometimes extended to the new fry for a while. The observation of this process will more than reward you for any effort necessary to keep these fish.

The next time you are in your favorite aquarium store, look at the tanks and try to place each fish you see in one of the groups we have just discussed. It may take some practice, but when you can do this with a fair degree of accuracy, you will have come a long way toward knowing which fish to take home and which to leave until next time. Back to Page 1>>

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Seven Families of Aquarium Fish

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Reader Comments

Julie    Gilbert, AZ

8/25/2009 6:16:40 PM

A lot of good information.

Dazzle    Fredericksburg, VA

2/5/2009 5:25:21 PM

:) Very nice. Glad to know you mentioned about feeding the bottom feeders such as the corydoras. Sad to see them starve to death...

Ken    Atlanta, GA

2/5/2009 6:10:39 AM

Very helpful information. I believe if one were to follow this information, it would prevent a lot of unfortunate aquarium incidents. Wish I had heard this years ago! Thanks.

Kay    Nashville, TN

2/4/2009 9:30:30 PM

Nice Article and filled with helpful information.

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