Rummynose Tetra (Petitella bleheri) is a South American characin native to blackwater and clearwater tributaries of the Rio Negro and Orinoco regions, where it lives in warm, acidic forest streams with soft water, submerged wood, leaf litter, and shaded margins.

This species is known for its bright red facial coloration, silver body, and sharply banded black-and-white tail pattern. The red head coloration is more than decorative; it often becomes stronger in settled, healthy fish and can fade when the fish is stressed or newly moved.

In the aquarium, Rummynose Tetras are valued for their tight schooling behavior and synchronized movement through open water. They are especially effective in planted community aquariums, where a group creates constant motion without overwhelming calmer tank mates.