Parosphromenus allani

Overview

Parosphromenus allani is a small black-water labyrinth fish from Sarawak. Males are more colorful, while females are difficult to separate from related species. Uncertainty over some populations makes locality and breeding records more valuable than broad sales labels.

Distribution & habitat

Type material came from the Sibu region of Sarawak, Malaysian Borneo, with further records elsewhere in the state. Fish labeled Stunggang or Lundu from the Batang Kayan area differ in tail and anal-fin pattern; whether all belong to this species remains unresolved.

Peat forests and connected black-water streams provide shade, very soft acidic water, and leaf cover. A Sibu collection came from ankle-deep still water beneath a bridge at pH 3.8–4.2. Clearing and land conversion have reduced habitat.

Aquarium setup

Allow about 40 × 20 cm for a pair. Wood, roots, leaves, and small containers create shade and caves; a bare bottom simplifies cleaning. Shade-tolerant plants and floating cover suit low light, while leaf microorganisms supplement fry feeding.

Acidic water with very low general hardness and negligible carbonate hardness may require a reverse-osmosis supply. Use a mature aquarium, gentle sponge filtration, and weekly changes of about 5–10%. Avoid delayed large changes. Filterless housing only suits lightly stocked pairs under strict feeding and maintenance. Routine care favors the cooler end of the suitable range, with modest warming for breeding.

Diet & feeding

It hunts tiny aquatic invertebrates and needs varied small live foods, including brine shrimp nauplii, Daphnia, Moina, mosquito larvae, and microworms. Most dry food is refused. Occasional acceptance of frozen food does not make it a sufficient sole provision.

Behaviour & compatibility

Pairs alone offer better chances of raising fry naturally. Mixed-sex groups are possible, but other adults usually reduce offspring survival. Any companions should be tiny, peaceful, and suited to the same water. Keep related species and uncertain locality forms separate to avoid confused females and hybrids.

Sexual dimorphism

Males are much more colorful; plain females are unreliable for stock identification. Population differences make a single fixed red-blue pattern unsuitable as a universal diagnosis.

Breeding

A male defends a small cave-centered territory and displays nearly vertically, head downward. Spawning embraces produce eggs attached to the cave ceiling. Some males add a few bubbles, while others do not. Inexperienced fish may dislodge or eat eggs.

The female guards outside afterward and the male tends the brood. Eggs hatch after about 24–36 hours. Young become mobile another four to six days later and leave fully swimming after a further three to five days. Start with microscopic foods such as Paramecium or rotifers, then brine shrimp nauplii. Complex mature aquariums may retain offspring; simpler ones favor separate rearing.

Notes

The initial hobby-magazine description contained limited diagnostic detail. Later work also faced uncertainty over locality forms and fin colors. Stunggang and Lundu should not be treated automatically as established synonyms.