Opsaridium tweddleorum

Opsaridium tweddleorum is a predatory cyprinid from the rivers of southern and central Africa, belonging to a genus of fast-swimming, piscivorous stream fish. It has a classically streamlined body plan with a pointed snout, large eyes, and a forked tail suited to rapid acceleration in flowing water. In the wild it forms schools in fast-flowing river channels and pools, hunting small fish and invertebrates. In the aquarium it requires a very large, well-filtered tank with strong water movement and high dissolved oxygen. Tankmates must be large enough not to be preyed upon. Feed on high-quality carnivore foods: frozen fish, prawns, krill, and meaty sinking pellets. A secure lid is mandatory. The species is rarely encountered in the mainstream hobby and is primarily kept by specialists interested in African river fish.

Water: Temperature 20–26 °C, pH 6.5–7.8, GH 5–15; strong flow; high oxygen essential. Tank: 200 L minimum; powerful filtration; open-water layout; very tight lid. Feeding: Frozen fish, prawns, krill, whitebait, and meaty pellets; carnivore diet required. Breeding: Not documented in captivity; open-water egg-scatterer in rivers. Compatibility: Predatory; must only be kept with large, robust fish of similar or greater size.