Axelrodia riesei · Ruby Tetra

Overview

Tiny and red-toned, Axelrodia riesei suits subdued lighting, mature soft-water conditions, and equally gentle companions. Its size does not remove the need for adequate aquarium space and stability.

Distribution & habitat

Known records are confined to the upper Meta east of Villavicencio in Colombia, within the Orinoco system. Blackwater habitat is reported, with small forested tributaries considered more likely than large channels; detailed habitat preferences remain uncertain.

Aquarium setup

Use sand, wood, roots, and leaf litter for cover. Microorganisms developing on decaying leaves provide supplementary food for fry. Low light, shade-tolerant plants, and floating growth suit the setup.

Breeding particularly requires acidic water with negligible carbonate hardness and very low general hardness, which may call for reverse-osmosis water. Sensitivity to changing organic waste levels makes a biologically mature aquarium essential.

Diet & feeding

It probably takes tiny invertebrates and zooplankton in nature. Suitably fine dry foods are normally accepted, alongside daily small live or frozen items such as Artemia nauplii, tiny water fleas, or small worms.

Behaviour & compatibility

Its peaceful disposition does not make it an all-purpose community fish. A species setup, or a few equally small gentle characins and catfish, is preferable. At least eight to ten reduce shyness. Rival males occupy small territories and spar, so social life is not constant synchronized schooling.

Sexual dimorphism

Adult males are slightly smaller and usually more intensely colored. Mature females are rounder, especially when gravid. Color differences among newly imported wild fish are not securely attributable to sex alone.

Breeding

Captive breeding is established, and a few young may appear spontaneously in a well-structured mature aquarium. Soft acidic water, fine-leaved plants, and microorganisms on leaf litter support the process. Adults in condition can spawn daily. For controlled breeding, place a pair or one male with several females in a separate setup, then remove adults after several days while eggs and fry develop there.

Notes

Red coloration varies in extent and strength and may fade after time in captivity. A deeper body and redder appearance help distinguish it from a similar congener, but one color observation is insufficient for dependable sexing.