An Introduction to Rainbowfish and Silversides

Professional Photographer: Aaron NormanThe tranquil and attractive rainbowfish and silversides can add beauty and interest to more difficult, more alkaline freshwater systems.

The Atheriniformes are a small group of bony fish that are mostly marine in circulation but do consist of a variety of freshwater types that have become moderately important aquarium fish. There are at least 8 households in the order Atheriniformes, however the only one of any fantastic significance is Melanotaeniidae. This household includes most (however not all) of the species commonly known as rainbowfish. Although many aquarists associate these fish with Australia, they are also to be found in New Guinea too. Really, New Guinea is home to among the most incredible of all the rainbowfish, the well-known red Irian rainbowfish Glossolepis incisus.

Just two other families offer up any consistently offered tropical fish, but these both give us just a single types each. From the Telmatherinidae comes the ever-popular Celebes rainbowfish Marosatherina ladigesi (in older books described as Telmatherina ladigesi), while a bit less frequently seen is the Madagascar rainbowfish Bedotia geayi from the family Bedotiidae. Another household of some significance in Australia is the Pseudomugilidae, or blue-eyes family, with a fair number of these beautiful little fishes being popular for fresh- and brackish-water aquaria. Unfortunately, couple of if any of these fish are regularly offered in my local (British) aquarium stores.

The Atheriniformes are carefully related to the Beloniformes (halfbeaks and flying fish) and the Cyprinodontiformes (killifish and livebearers), and together they form a big group known as the Atherinomorpha. As a group they can be defined as residents at the surface area, and most are adapted to feed upon the algae, plankton, or small animals such as pests that are to be discovered there.

The aquarist can spot some other resemblances, too. They all have a body morphology somewhere between that of primitive fish like characins and advanced fish like cichlids. Unlike characins, but like cichlids, their pelvic fins are close to the front of the fish. If you look at a primitive fish like a characin or catfish you’ll discover that the pelvic fins are set way back along the body close to the tail. The Atheriniformes in particular likewise share another similarity with sophisticated fish: they have not one, however 2 dorsal fins. However in other methods the Atherinomorpha are less innovative than the cichlids or any of the other perch-like fishes. They do not have such complicated mouthparts, for instance, and the dorsal and anal fins lack the durable, protective spines so normal of perciform fish.