Parosphromenus bintan

Overview

Parosphromenus bintan is a tiny specialist of very soft acidic black water. Males have rounded tails with concentric pale, black, and blue-green bands. Its name is often applied loosely, making provenance essential when keeping and breeding similar-looking fish.

Distribution & habitat

Confirmed localities are Bintan in Indonesia's Riau Archipelago and Bangka. Similar fish from Sumatra and Borneo have uncertain identities and should not automatically extend the confirmed range.

Peat-swamp forests and connected streams provide dense shade and dark, mineral-poor acidic water. Some habitat has been reduced to modified channels and remnants, without removing the species' specialized requirements.

Aquarium setup

Allow about 40 × 20 cm for a pair. Roots, wood, leaves, pipes, and small containers provide refuges and overhead spawning surfaces. A bare bottom is an option. Shade-tolerant and floating plants add cover under subdued lighting; leaf microorganisms supplement fry food.

Maintain acidic water with extremely low general hardness and negligible carbonate hardness, potentially using reverse osmosis. A mature aquarium is essential. Gentle sponge filtration and weekly changes of about 5–10% avoid the disruption of irregular large changes. Filterless pairs are possible only with strict feeding control and maintenance.

Diet & feeding

It mainly hunts tiny aquatic invertebrates. Provide varied small live foods, including brine shrimp nauplii, Daphnia, Moina, mosquito larvae, and microworms. Most dry foods are rejected, and occasional frozen-food acceptance should not replace a suitable live menu.

Behaviour & compatibility

Quiet species-only pair housing improves chances of natural fry survival. Mixed-sex groups are possible, but extra adults usually reduce success. Do not combine related species because females resemble one another and hybridization can occur. Any companions must be very small, peaceful, and compatible with the specialized water.

Sexual dimorphism

Male unpaired fins show a narrow pale edge, black band, blue to greenish-blue iridescence, and a broad dark inner area. Pelvic fins are blue-green with white filament tips. Females lack bright bands and become pale beige near spawning. Mood also changes coloration.

Breeding

The male displays head-down and establishes a territory around a small cave. Temporary pairs attach eggs to its ceiling after spawning embraces. A small bubble nest may be built, but bubbles are not obligatory. Inexperienced fish may lose or eat eggs.

The female guards outside while the male tends the brood. Hatching takes about 24–36 hours; mobility follows four to six days later, then complete free swimming after another three to five days. Care ends when the young leave. Begin with Paramecium or rotifers, soon adding brine shrimp nauplii. Structured mature systems may retain fry beside parents; simpler ones favor separate rearing.

Notes

The rounded tail has no filamentous central ray. Blue line and Selatan labels do not establish confirmed identity. Preserve full fin-pattern information together with trustworthy locality records.