The fish in this popular group belong to the family Cyprinidae and is found in Sri Lanka and India, in slow moving coastal rivers. These fishes have two things to offer the fishkeeper: active movement in the aquarium, and a willingness to breed. Their slim bodies, flattened dorsal surfaces, and slightly upturned mouths indicate that they inhabit the upper levels of the water. Like all cyprinids, they do have a tendency to eat their own eggs immediately after spawning. There are several methods of preventing this from happening in the aquarium. You can use physical barriers, such as a layer of marbles on the tank base, or a suspended netting cage that separates the parents from their eggs. Many danios can be spawned as a group, rather than just one pair at a time.
This very active pearl danio has an alongated gray-green body with some iridiscences. Under side-lighting, pearl danios have a beautiful pearl blue-violet hue, with a red-gold line running along the rear half of the body. The gill cover shimmers metallic blue. Two pairs of barbels are present. The fins are mostly translucent green, but with a red tinge at the base. The female can be distinguished by her deeper body.
This is one of the old favorites among aquarium hobbyists. It has good reason to be popular: it is peaceful, active, easy to reed and colorful. It is at home at any aquarium, as long as it is not too small for its size and active habits. Unless it is abused pretty badly, it is seldom attacked by disease. The Giant danio lays adhesive eggs in the manner of the barb species. A thicket of bushy plants is placed at one end of a large aquarium in a sunny spot. The water should always be fresh and clear, and the bottom may be covered with glass marbles or pebbels, because the fish sometimes will spawn in the open areas and the eggs could be eaten. Driving is very active, and hundreds of eggs often result. When finished, the parent fish should be removed.
Bengal danio (Danio devario) is a slightly smaller fish than Giant Danio (Devario aequipinnatus) and its colors are not as brilliant. Like the Giant danio it is a very active species and could easily cause a tankmate with more sluggish habits to become very nervous. It is always a good policy when mixing fishes in a so-called "community aquarium" to pay attention not only to whether the fishes will hurt each other or not but also to choose fishes with almost equal dispositions. There is no place for a nervous, timid fish in the same tank as such everactive fellows as the danios. It would not be able to stand the constant hustle and bustle and would not get anywhere near its share of food. (Photos courtesy of fishdb.sinica.edu.tw)