Parosphromenus harveyi

Overview

Parosphromenus harveyi is a small black-water labyrinth fish associated with northern Selangor peat forest. A male's plain blue pelvic fins with exceptionally long filaments, and a broad black band near the tail edge, are useful identification clues.

Distribution & habitat

The type locality is Batu Arang, Selangor. Further records lie in northern Selangor peat swamp, with a population around Tanjong Malim in Perak. Forest clearing and other alterations have removed substantial habitat.

Typical water is shaded, strongly stained by organic decomposition, extremely mineral-poor, and acidic. Occurrence in remnant channels does not establish tolerance of ordinary hard tap water.

Aquarium setup

Allow about 40 × 20 cm for a pair. Roots, wood, leaves, pots, pipes, and small containers provide shade and spawning caves. A bare bottom aids cleaning. Shade-tolerant and floating plants add cover, while leaf microorganisms supplement fry food.

Very soft acidic water with negligible carbonate hardness may require reverse osmosis. Only use an established aquarium, with gentle sponge filtration and weekly changes of about 5–10%. Filterless housing demands low stocking, controlled feeding, and rigorous maintenance. Avoid delayed, large water changes.

Diet & feeding

It hunts tiny aquatic invertebrates and needs varied small live foods such as brine shrimp nauplii, Daphnia, Moina, mosquito larvae, and microworms. Most dry foods are rejected; occasional frozen-food acceptance should not make them the entire menu.

Behaviour & compatibility

Species-only pair housing preserves identity and offers better chances for offspring to grow beside their parents. Mixed-sex groups are possible, but additional adults usually reduce fry survival. Separate related species because females are difficult to distinguish and hybridization is possible. Any companions must be tiny, calm, and suited to the same water.

Sexual dimorphism

Male unpaired fins have black near-edge bands bordered by blue iridescence, broader on the inner side. Pelvic fins are plain blue with long filamentous tips. Females lack bright bands and become pale yellow near spawning. Both sexes can display an oblique eye stripe and rapidly change color with mood.

Breeding

Males establish cave-centered territories and court head-down with spread fins. Temporary pairs attach eggs to the cave ceiling after embraces. A few bubbles may be used, but they are not obligatory. Inexperienced adults sometimes lose or consume eggs.

The female guards outside while the male cares for the brood. Hatching takes approximately 24–36 hours. Movement begins another four to six days later, followed by a further three to five days before complete free swimming and departure. Care then ends. Begin with Paramecium or rotifers, soon adding brine shrimp nauplii. Simple aquariums favor separate rearing; complex mature ones may support natural survival.

Notes

Limited early diagnostic detail was supplemented by later observations of long pelvic filaments, a broad tail band, and rounded tail shape. Preserve reliable locality information rather than identifying stock solely from females or sales photographs.