Danios are part of the Rasbora family of Cypriniformes, and originate from streams and small rivers in Asia, particularly around Sri Lanka, Malaysia, and India. The most famous of all the danios is the Zebra Danio, which is bred in huge numbers both for the aquarium trade and for genetic research. The fish has importance in genetics since it is a manageable, robust, species and can be bred in successive generations relatively quickly.
Whilst experiments with live animals for genetics research have their importance, the resulting strains should never be released into the public domain for the purposes of making money in the pet trade. This has unfortunately already happened with the Zebra Danio, and it is possible to obtain genetically modified strains with ‘glowing’ colours. Thankfully, most fish keepers in this country would not be too happy with such fish being sold, and we have yet to see any on sale.
Danios are active fish, and will continually dart around the aquarium interacting with each other, searching for food, and swimming against any available flow of water. Because of this natural behaviour, the fish must be kept in groups comprising of at least six for the smaller species, and at least four or five for larger danios