Acanthurus leucosternon

The Powder Blue Tang is a highly sought-after but demanding species best suited for veteran marine aquarists. In its natural habitat across the Indian Ocean, it inhabits shallow, clear reef flats and slopes with strong water movement. Replicating this environment is key to its success in captivity. A very large and long aquarium is not just a recommendation but a necessity, allowing for the vast, open swimming lanes this incredibly active fish requires. Strong, turbulent water flow is crucial, as it mimics its native currents and ensures the high levels of oxygenation needed to support its high-energy lifestyle and metabolism.

Physiologically, this tang is a dedicated grazer. Its diet in the wild consists of filamentous algae and biofilm found on rocks and substrate. In an aquarium, this behavior must be supported with multiple daily feedings of high-quality, marine-based herbivorous foods. Dried marine algae (nori) clipped to the rockwork is essential, allowing the fish to graze continuously as it would naturally. This should be supplemented with prepared foods like pellets, flakes, and frozen formulas specifically for herbivores. A well-established tank with healthy live rock can also provide a natural foraging ground.

This species' social behavior is a critical consideration. It is aggressively territorial, particularly towards other surgeonfish and any fish with a similar body shape or feeding habits. It is almost always recommended to keep it as a solitary specimen of its genus unless the aquarium is of an exceptionally large, commercial scale. Introducing the tang last into the community can sometimes temper aggression, but its innate territorial drive remains. Due to its high metabolism and constant feeding, it produces a substantial amount of waste, placing a heavy load on the filtration system. Therefore, an oversized protein skimmer, a capable biological filter, and a rigorous schedule of large, regular water changes are non-negotiable to maintain the stable, pristine water parameters it demands. Its sensitivity to common marine parasites, particularly during acclimation, further cements its status as a fish for experts only.