Brittanichthys axelrodi is one of the rarest and most extraordinarily beautiful small tetras in the aquarium hobby. Named in honour of Dr. Herbert R. Axelrod, the legendary ichthyologist and aquarium author, it is a tiny blackwater species from the Rio Negro drainage of Brazil reaching only about 3.5 cm. Its vivid blood-red body and electric blue horizontal stripe, most intense in males, create a colour combination of breathtaking intensity in a well-lit blackwater nano setup.
This species demands highly specialised, extreme blackwater conditions: very soft water approaching distilled, very low pH (3.5–5.5), warm temperature, tannin staining, and dim lighting with dense floating plant cover. It is exquisitely sensitive to water quality deterioration and should only be kept in a mature, biologically stable aquarium. It belongs to the same ecological guild as Paracheirodon simulans and Dicrossus species in the Rio Negro.
Brittanichthys axelrodi is rarely available in the trade and commands premium prices when it appears. It is strictly for advanced blackwater specialists who can provide and maintain the extreme soft-water conditions it requires. In the right environment, a school of 10 or more is one of the most spectacular sights in the freshwater aquarium hobby.
