The Tench is a traditional pondfish (predominantly in Europe) that is gradually making a transition to (large) aquaria. Until the mid-1990s two color forms were available: the green (or wild type) and a golden (sometimes mottled) variety Since then, at least two other colors have become available: a deep orange (sometimes referred to as red) and an orange/red and white type.
Two color types of this popular fish are available: one with light-colored anal and dorsal fin edges and one with red edges. A long-finned variety that almost disappeared during the early 1990s is now found with greater frequency once more.
The Rudd is a stocky, deep-bodied fish. It has an olive-colored back, silvery-green sides, and a silvery-white belly. The species is available in the hobby in two color forms: the silvery wild type and a cultivated golden form. It is the latter that is kept, primarily by European pondkeepers, but to an increasing extent by aquarists as well.
Despite it being a long-established aquarium fish, there is still debate regarding the correct scientific name of this species, with the weight of opinion tending toward R. sericeus. Males look particularly attractive during the breeding season (April to August) and when they are subjected to side lighting.
Without being one of the most colorful of the rasboras, this species is one of the most beautiful when in peak condition and under appropriate lighting. It has a dark pink arched body. The fins have dark orange streaks, and its eyes are metallic orange in color. It is a challenging fish best avoided by less experienced aquarists.
This is another of the larger rasboras (although the maximum size is rarely attained, either in aquaria or in the wild). It is a species that only looks at its best when kept in a shoal. It prefers the middle and upper reaches of the aquarium but will also venture farther down.
Under appropriate conditions the Glowlight Rasbora really lives up to its name. Unlike other rasboras, however, this species can tolerate relatively low temperatures during the winter, something that may improve the chances of achieving breeding success, particularly if pairs are allowed to select themselves from a shoal.
The Harlequin is one of the old aquarium favorites, having first been imported into Europe way back in 1906. It is still very popular today, largely owing to its striking coloration and dark body cone. Of the three “harlequins,” this species possesses the widest body cone, making it immediately identifiable. A dark or blue variety is now also widely available.
This is a slender fish that only looks its best when water and tank conditions are right. At other times the red coloration responsible for the common name, and which makes a shoal of these rasboras an absolute delight, fades significantly.
The Fathead Minnow was originally cultivated commercially in the United States as a bait fish. However, the attractive coloration of the golden morph, added to its interesting breeding habits, soon created a demand among aquarists. Today, virtually all the Fathead Minnows in the hobby are of the golden variety.