Red Eye Tetra

Geographic Origin and Biotope: River basins of Paraguay, Parana and Uruguay, in eastern South America. Ranges from clear waters in Brazil to subtropical swamps (Pantanal), tolerating strong climatic variations.

Taxonomy and Morphology: Red-eye Tetra (Moenkhausia sanctaefilomenae). Classic "battle" tetra. Has a decidedly more stocky, convex body and large scales (like its cousin pittieri) compared to thin tetras like neons.

Social Behavior: Dynamic gregariousness (shoaling). Incessantly explores every crevice of the tank. Tends to "detach" from the school if there are few specimens (minimum 6-8) annoying other inhabitants out of boredom.

Coloration and Sexual Dimorphism: Simple but high contrast. Metallic gray/silver livery, with a large vertical black band (followed by a white one) on the base of the tail. Standout feature: the bright red semicircle on the upper area of the eye (Red Eye). Females very swollen and stocky.

Aquarium Setup: Aquarium of at least 80 cm (32 inches), set up in planted river style: intricate roots and woods, leaves on the bottom and a clear frontal area for long swimming sprints. Can tear thin leaves if hungry.

Diet and Feeding: Totally unproblematic. Anything that falls into the tank: granules, flakes, frozen brine shrimp, peas. Greedy eater who will rise to "boil" on the surface at mealtime.

Water Quality: Armored fish. Among the most tolerant of South American characins, it tolerates ph from 6.0 to almost 8.0, and significant thermal swings (being of subtropical origin, it prefers water not too warm, max 25°C / 77°F).

Compatibility and Tankmates: Watch out for long fins. Has a reputation as a "Fin-nipper". Keep away from Angelfish, Guppies or Gouramis. Ideal for robust tanks with Plecostomus, large Central American Cichlids (Thorichthys) or Barbs.

Aquarium Reproduction: They release many eggs among the moss (Java Moss) at dawn, often after a massive cold water change. The eggs hatch quickly and the fry require infusoria. The breeders will avidly eat the brood.

Risks and Diseases: Dwarfism and chronic stress in cramped spaces. Frequently sold for 30-liter (8 Gallons) tanks "because it is small". If trapped, it will bite anyone to death, fade and develop bacteriosis due to excessive pollution (it has a very high metabolism).