Every community fish tank can use a pair or more of loaches. These oblong, rounded back fish with flattened bellies will quickly become the tank characters, lying on the bottom snuffling into the gravel for bits of food, taking up hiding posts behind rocks or in improvised caves, or in the case of the clown loach, taking a break by lying on its side. These fish are easy to keep – if the water is kept clean and fresh – and fun to watch. Clown loach. The most popular aquarium species is the clown loach. With its gold body, five to 10 inches long, and three black vertical stripes – one that goes down across the eye – it looks like a tiger barb that was stretched out of shape. Like the other loaches, the clowns do best in pairs or small schools and together they'll patrol the tank bottom, returning once and again to the safety of their chosen hideout. If your tank is small, the loaches may be less than hospitable to other fish that try to enter their bottom territory. Otherwise, they're usually fine with most species. The first time you see one of your loaches lying on its side on the bottom will be disconcerting, but it's not an unusual behavior for them.
All but a few of the more than 200 species of loach come from central and southern Asia. Relatives of the catfish, they have oval, sucker-like mouths with whisker-like barbels on either side. Being mainly nocturnal, they use these whiskers to search for food. Native to swift flowing waters, some of these fish grow to three feet long in the wild. In the aquarium they remain small, usually no more than a six inches.
Several species are available for aquariums and all of them have similar requirements: medium pH and a temperature of about 76 degrees. They will feed, like catfish, off the flakes of food that float to the bottom of the tank. They are also ardent worm eaters. Whatever you feed them, consider using a gravel of a fine consistency rather than hard-edged pebbles since the fish can injure themselves digging into the gravel for food. Being scavengers they will help clean up food that other fish may miss.
Types of Loaches
Coolie loach. Another favorite is the coolie loach. A smaller fish that grows to only three to four inches, the coolie loach is pink with several black vertical bands. It moves with a fascinating snakelike motion and a few together make for great fish watching.
European weatherfish. One of the largest of the aquarium loaches, the European weatherfish grows to some eight inches. It has brown speckles over a yellow-brown body. If you live in a hurricane zone, you might keep an eye on your weatherfish. These fish become highly active as the barometric pressure drops before an approaching storm.
Not Easy to Breed in Aquariums
Loaches are rarely successfully bred in aquariums since older, larger fish are best for breeding. This size difference, however, has helped keep the wild populations stable despite intensive harvesting. Aquarium keepers only want the small fish for their tanks so harvesters leave the larger breeding fish alone.