The Scarlet Badis (Dario dario) is a tropical freshwater fish and one of the smallest known percoid fish species. It is a micro predator, feeding on small aquatic crustaceans, worms, insect larvae and other zooplankton.
Appears to be restricted to tributary systems draining into the Brahamaputra River in parts of West Bengal and Assam states, India although it may also range into Bhutan.
Scarlet Badis are among the smallest percoid fish species. Males usually do not exceed 2 cm (0.79 in), with the females being even smaller around 1.3 cm (0.51 in). Apart from the size difference, the sexes are easy to distinguish by the vibrant colours and prominent fins of the male.
Typically inhabits shallow, clear water streams with sand or gravel substrates and dense growths of marginal and aquatic vegetation. At one locality the macrophyte assemblage included members of Hygrophilia, Limnophila, Ottelia, Rotala, and Vallisneria.
The Scarlet Badis is becoming increasingly popular as an aquarium fish, particularly in nano aquaria. Their territorial nature does however mean that their environment must contain sufficient boundaries to prevent aggressive behaviour, especially between males of the species. The careful aquarist would ensure that the tank is sufficiently filled with items of decoration capable of breaking up lines of sight and establishing territories. natural driftwood or coconut shells used as caves are all ideal.
This species is very easy to sex but often only males are traded.
Females are smaller, less colourful (they do not have any red or blue pigmentation on the flanks and only indistinct bars or none at all) and possess a noticeably shorter, stumpier-looking body profile than males. In addition, males develop extended pelvic, dorsal and anal fins as they mature.