Parasphaerichthys lineatus

Overview

Parasphaerichthys lineatus is a minute labyrinth fish with a dark lengthwise flank stripe instead of the eye-like spot seen in its relative. Slow movement and a retiring disposition make it vulnerable to competition. It benefits from conspecific interaction without forming a tight school, and its breeding behavior is unusually flexible.

Distribution & habitat

The confirmed type locality is Hmoain pool near Einme in the northern Irrawaddy delta, Myanmar. Its wider delta distribution remains incompletely understood. Clear water, mud, and dense aquatic vegetation characterize the recorded site; a chocolate-gourami sales label does not imply a need for dark black water.

Aquarium setup

A small group needs at least about 40 × 20 cm of floor space. Dense planting and a soft bottom are appropriate, though fine gravel is acceptable. Roots, floating plants, modest leaves, and small pipes provide complexity and refuges. Keep circulation gentle and avoid heavy tannin staining.

Provide a relatively cool seasonal period lasting several months rather than maintaining warm conditions throughout the year, which may reduce breeding success and lifespan. Changes should be gradual; a sudden temperature drop does not substitute for a sustained cooler season.

Diet & feeding

It primarily hunts small aquatic crustaceans, worms, insect larvae, and other zooplankton. New arrivals may refuse prepared foods, although some learn to accept them. Provide daily suitably small live or frozen foods such as brine shrimp nauplii, Daphnia, and microworms.

Behaviour & compatibility

Larger or busier companions can intimidate it and monopolize food. A species aquarium favors reproduction; any companions should be tiny and peaceful. At least six conspecifics provide useful social interaction, despite the absence of true schooling behavior.

Sexual dimorphism

Mature females are noticeably larger and deeper-bodied when carrying eggs. Courting males briefly become black-headed and bright orange, accompanied by audible croaking.

Breeding

A pair defends a small area, usually spawning close to the bottom or inside shelter. Both egg release during an embrace and successive batches fertilized by the male have been observed. Eggs may be moved into floating or submerged bubble nests, shallow bottom depressions, or filter-sponge pores. The latter locations may be used without bubbles.

Care may involve both adults or only the male, and eggs can stay in one place or be moved repeatedly. Hatching takes about three to five days; free swimming follows around seven to ten days after laying, when parental care ceases.

Fry require microscopic foods such as Paramecium or rotifers initially, followed by microworms and brine shrimp nauplii as they grow. Separate egg rearing is possible, while a mature planted aquarium may retain some young naturally. No single nest location describes every successful event.

Notes

The labyrinth organ is present, although surface gulping is less frequent than in many familiar labyrinth fishes. Small size, a lengthwise stripe, and absence of a flank ocellus distinguish it from Parasphaerichthys ocellatus.