Rasboras are all you need to fill your tank with living color. Few freshwater tropical fish are as bright, animated, peaceable and easy to care for. Members of the same Cyprinid family as tetras, rasboras come from south and southeast Asia where they live in slow moving streams, dense with vegetation. When well-fed (and these little fish can eat a great deal) and in good condition, these fish display sharp bright background hues, that seem to be illuminated from within, and distinctive black markings.
While some dozen species are imported, a few of the most popular and easy to find are the harlequin rasboras, the red-lined rasbora, the scissortail, the two-spot and the pygmy. They vary in color and size. Harlequin. The harlequin (also called the red rasbora) gets its name from its ruby red body color and its elongated triangle-shaped black "harlequin" spots on its body. It has a silver belly with a gold rim to its fins. This variety grows to about one and a half inches in length.
Red-lined. The red-lined rasbora has a salmon to pink lateral line going from its head to its tail. Its body is a light gold. The red-lined grows about the same size as the harlequin.
Pygmy. The pygmy is yellow with black spots and is slightly smaller than the harlequin or red-lined varieties.
Scissortail. The scissortail is a larger member of the group, growing to six inches. The scissortail has black spots on its widely separated tailfins. If you are going to keep a school, its best to have a longer tank in which they can roam.
Two-spot. The two-spot is a pale-white fish with a dark spot at the center of its body. This variety is one of the largest, measuring up to eight inches in length. As with the scissortail variety, if you are going to keep a school, its best to have a longer tank in which they can roam.
Rasboras Need to School
Rasboras are schooling fish and so the fish and your tank will suffer from having only one or two. Begin with no fewer than three and, once these are acclimated to the tank, add another few to the school. Seven or eight of these lovely fish swimming together in a well-planted aquarium will be great fun to watch. You may even decide, as some aquarists do, to add to the school and keep only rasboras in your tank.
Easy fish to maintain, rasboras do well at temperatures of around 74 degrees Fahrenheit and don't seem to suffer if the temperature changes a couple of degrees above or below that. The tank's pH should be a moderate 6.5, erring, if anything, to the acidic side since the streams they live in are usually choked with decaying vegetation, which raises the acidity of the water.
Rasboras are insectivorous but do very well on fine flake food. They have good appetites but as with any aquarium fish, feeding a little at a time more often is better than giving a lot at once. When that happens, uneaten food sinks to the bottom of the tank and decomposes there.