An aquarium dealer need only look at the length of the stock list his favorite wholesaler has just faxed over to see what an enormous variety of tropical fish are on the market today. To a new hobbyist, the choices must seem endless, and yet depending on where he wants to take his new hobby, some choices will be much better than others. Here's a list that might help you match a great fish to your customer's special niche.

Great Fish for breaking in a new tank: Black Tetras (Gymnocorymbus ternetzi) Getting a new aquarium through its break-in cycle can be a rather harrowing experience for both fish and fishkeeper. But unlike many of their flashier cousins, black tetras seems to be totally unfazed by the rising ammonia and nitrite levels that plague the new setup. They have hearty appetites, are active without driving the other residents up the wall, and make interesting, if not spectacular aquarium fish. As with most schooling fish, they should be maintained in a group of 4 or more, so no individual can dominate the others to the point of exhaustion.

Black tetras have a more striking appearance when young, with darker black stripes contrasting the silver background. They are also obtainable in a white form (cleverly marketed as the White Tetra), and both black and white varieties are also available in a long-finned version, often called Black Skirts and White Skirts respectively. Sadly, these fish are sometimes sold painted or dyed with bright col ...