Zebra danio

The zebrafish is arguably the most widely studied fish in scientific research and among the hardiest, most forgiving species a beginner aquarist can choose. Native to slow-moving streams, seasonal pools, and mature rice paddies in northern India, Bangladesh, and possibly Bhutan, it reaches a standard length of about 5 cm, a size that makes it suitable for community tanks of all scales. The familiar horizontal blue-and-white striped pattern is present in both sexes, though males tend to be slimmer and more intensely coloured, while females are rounder-bellied and slightly larger. A tank with a base of at least 90×30 cm, roughly 81 litres, is appropriate for a school of eight to ten zebra danios. These are active, surface-oriented swimmers that appreciate a well-planted aquarium with some open water and moderate flow. The species is cool-water tolerant: while its native waters reach over 38°C in summer, it thrives in the aquarium at 18–25°C, a range that often eliminates the need for a heater in indoor tanks. pH of 6.0–8.0 is tolerated with no issue. Zebra danios are micropredators that feed on aquatic crustaceans and insect larvae in the wild, but they accept any dried, frozen, or live food in captivity. Their temperament is exceptionally peaceful, making them compatible with most small community fish — tetras, rasboras, Corydoras, dwarf cichlids, and loaches. Always keep them in a group of at least eight; single specimens become stressed and hide. Breeding is straightforward: a separate shallow tank with a mesh base, marbles, or a layer of java moss, and adults are removed after spawning. Eggs hatch in 24–36 hours, and the fry become free-swimming within a few more days.