Brachydanio kerri

Brachydanio kerri, commonly known as the Blue Danio or Kerr's Danio, is a small and vividly coloured species from clear hill streams on the Malay Peninsula and surrounding islands. Its most immediately striking feature is its deep, saturated sky-blue body — a more uniform and intense blue than the iridescent striping seen in most danios — with a delicate yellow or gold mid-lateral line adding a warm accent.

In the aquarium it is a peaceful, active schooling fish that behaves identically to other small danios. It does best in a group of eight or more in a planted tank with good water quality. The blue colouration is most intense in well-conditioned fish maintained in clean water with a varied diet, particularly one that includes live or frozen foods.

Despite being described in the literature since 1929, Brachydanio kerri remains less well-known in the hobby than Zebra or Pearl Danios. It deserves far wider appreciation as a beautifully coloured, easily maintained nano-community species.