Gastromyzon Extrorsus

Datasheet

General Description

The Gastromyzon Extrorsus, a member of the Cypriniformes order, is distinguishable by its brown body with thin gold stripes and a dark brown head dorsum with gold reticulate pattern. These fish typically reach a maximum size of 8.0cm and are endemic to Borneo, specifically the Kimanis and Petagas River basins in western Sabah, Malaysian Borneo. They are part of the Gastromyzontidae family, characterized by their flattened body, horizontally orientated paired fins, and fused pelvic fins forming a sucking cup adaptation for clinging to solid surfaces.

Aquarium Setup

For an ideal aquarium setup, ensure clean and well-oxygenated water with an oversized filter providing a turnover of 10-15 times per hour. Incorporate gravel, sand, or a mix of both with water-worn rocks and pebbles. Aged driftwood can be added, and artificial lighting should be strong to promote algae growth. Utilize adaptable aquatic plants like Microsorum, Crinum, and Anubias spp. while maintaining stable water conditions.

Behaviour

Gastromyzon Extrorsus are peaceful but territorial to some extent, with individuals showing varying levels of protectiveness over their space, particularly prime feeding spots. They tend to exist in loose aggregations and are more active when kept in groups of four or more. In the wild, they face competition from species like Lobocheilus bo and Paracrossocheilus acerus within their fast-flowing stream habitats.

Feeding and Diet

The diet of these loaches consists of benthic algae and micro-organisms, which can be replicated in captivity with high-quality dried foods, live or frozen bloodworms, and home-made gelatin-bound foods rich in vegetables and Spirulina. Maintaining a mature aquarium with ample algae-covered surfaces is crucial for their long-term health.

Reproduction & Dimorphism

Breeding Gastromyzon Extrorsus in captivity remains a challenge, with limited successful attempts reported. Observations with related species suggest that females are generally heavier-bodied and slightly larger than males. Successful breeding efforts have involved varying methods such as adjustments in water temperature, aquarium setup, and diet to mimic natural conditions.

Habitat and Distribution

These fish are found exclusively in swift, shallow streams with clear, oxygen-saturated water throughout the hill regions of Borneo. They are commonly observed in riffles and runs, preferring substrates of gravel, rocks, and boulders covered with algae and other micro-organisms. Gastromyzon Extrorsus is endemic to Borneo, particularly the Kimanis and Petagas River basins within western Sabah, Malaysian Borneo.