Axelrodia stigmatias

Overview

Tiny and silvery yellow, Axelrodia stigmatias shows a dark lower tail-base marking below an iridescent patch. A species setup or very gentle miniature community suits it better than a busy mixed aquarium. Its small size comes with a need for mature filtration and stable soft-water conditions.

Distribution & habitat

Confirmed records include Brazil’s Madeira, the Manacapuru lake complex beside the Solimões upstream of Manaus, and Peru’s Ucayali. Blackwater habitat is reported, and smaller forest tributaries are considered likely, though detailed habitat preferences remain uncertain.

Aquarium setup

Arrange sand, wood, and roots into a sheltered environment. Leaf litter adds cover and supports microorganisms useful to fry. Subdued light with shade-tolerant and floating plants is suitable.

Avoid immature aquaria because changing organic waste levels are poorly tolerated. Breeding requires acidic water with very low general hardness and negligible carbonate hardness, potentially prepared using reverse osmosis. Stability matters more than repeated rapid adjustment.

Diet & feeding

Tiny invertebrates and zooplankton are probable natural foods. Fine dry products are usually accepted, with daily small live or frozen items such as Artemia nauplii, tiny water fleas, and small worms.

Behaviour & compatibility

Peaceful toward other species, it is nevertheless unsuitable for a forceful or very active community. At least eight to ten help reduce shyness. Males maintain small territories and spar, rather than the group always moving in a tight school. Equally small, gentle characins and catfish are the safer companions.

Sexual dimorphism

Mature females are expected to look rounder, particularly when gravid. Color variation among newly imported wild fish is not securely linked to sex, so tail-patch color alone is unreliable.

Breeding

Captive reproduction is established, and a few fry may appear in mature, well-sheltered setups. Soft acidic water, fine-leaved plants, and leaf-associated microorganisms support breeding. Adults in condition can spawn daily. A pair or one male with several females may be placed in a separate aquarium, then removed after several days while eggs and fry remain.

Notes

It is more slender and silvery yellow than a similar red congener. The reason for variation in its iridescent tail-base patch remains unresolved; locality, diet, and individual variation cannot each be assumed to explain it.