Scarlet badis

The scarlet badis (Dario dario) is one of the smallest percoid fishes known, reaching a maximum standard length of just 20 mm. It is native to the Brahmaputra River drainage in West Bengal and Assam states of India, where it inhabits shallow, clear water streams with sand or gravel substrates and dense growths of marginal and aquatic vegetation including Hygrophila, Limnophila, and Rotala. Males are strikingly beautiful, displaying vibrant red and blue coloration with a series of seven iridescent blue vertical bars on the flanks — a pattern unique to this species among its congeners. Females are smaller and much plainer, lacking red and blue pigmentation. The scarlet badis is a micropredator that feeds on small aquatic crustaceans, worms, and insect larvae, and in captivity requires a steady supply of live or frozen micro-foods such as Artemia nauplii, Daphnia, and microworm. It is a retiring, slow-moving fish that is easily outcompeted by more boisterous tankmates, making it best suited to a dedicated nano-aquarium or a carefully chosen community of small, peaceful species. Rival males can be highly aggressive toward one another, and only a single pair or one male with several females should be housed in smaller aquaria. A pair requires a tank with base dimensions of at least 45 × 30 cm furnished with dense planting and plenty of cover including Cryptocoryne, Microsorum, and leaf litter.