These colorful, hardy fish fare best in groups of six or more fish. Rasboras are rewarding fish when maintained in the planted community aquarium, displaying beautiful coloration, and unique color patterns. Most of the rasboras are small, up to 10 cm long. They share the same family with many popular aquarium fishes such as the goldfish, koi, barbs, tetras and danios. Rasboras are the ideal fish for the community aquarium as most are small, peaceful, colorful and easy to care for.
In their natural environment many come from soft, slightly acid water. In an aquarium they are tolerant of most aquarium conditions as long as the water is well-filtered and partial water changes are conducted regularly. Rasboras are considered very hardy fish and can tolerate a wider pH range of 5.5 to 7.8, and hardness ranges from zero to 15°dH. The temperature range for Rasboras is around 22°C to 27°C.
They are fast and active shoaling fish, and should be kept in a group comprising a minimum of six individuals, though shoals of larger numbers are preferable not only from the standpoint of the well-being of the fish, but from an aesthetic standpoint - a large shoal of Rasboras presents a striking vista even to non-fishkeepers, and their active disposition in the water adds to the spectacle. Being a peaceful species, the Rasboras may be maintained in a community aquarium setup with other similarly sized and peaceful aquarium fishes, including many of the small Tetras, Danios, Pencilfish, Corydoras, Plecos and others.
An aquarium intended to house Rasboras should be well planted with some open areas for swimming. Most Rasboras are egg-scattering spawners, however, in some types of rasboras species (such as Harlequin Rasbora), they will deposits adhesive eggs on the underside of the leaves of plants such as Cryptocoryne and Aponogeton, these being among the plants that inhabit the Rasbora's native waters.
The female will swim in an inverted position beneath a chosen leaf, rub her belly along the leaf in preparation for spawning, this action seemingly encouraging the male to join in spawning. When the male joins the female, he adopts a similar inverted position alongside her, and as the female extrudes her eggs and attaches them to the underside of the leaf, the male curls his tail fin around the body of the female and with a trembling motion, emits the sperm that will fertilize the eggs.
The freshwater fishes repeat this course of action over a period of 2 hours or more, during which a large and well-conditioned female may deposit as many as 100 eggs. The lifespan of Rasboras has not been systematically determined, but individuals in the aquarium can be expected, with good care, to live for 5 to 6 years.