Hypergastromyzon Humilis

Datasheet

General Description

Hypergastromyzon humilis is a species of loach belonging to the Gastromyzontidae family within the Cypriniformes order. It is primarily found in swift, shallow forest streams in the Sungai Melawi river basin in Kalimantan Barat, Indonesian Borneo. This small species has a maximum size of approximately 3.5cm and is characterized by its specialized morphology adapted for life in fast-flowing waters, such as horizontally oriented paired fins, a flattened body, and fused pelvic fins forming a powerful sucking cup.

Aquarium Setup

For setting up an aquarium for Hypergastromyzon humilis, it is crucial to maintain clean and well-oxygenated water, achieved through an oversized filter with a turnover rate of 10-15 times per hour. The substrate can consist of gravel, sand, or a mix of both with the addition of water-worn rocks and pebbles. Aged driftwood is recommended, and the tank should feature strong lighting to promote algae growth, which serves as a natural food source. Aquatic plants can be included, with adaptable genera like Microsorum, Crinum, and Anubias species being suitable. A tightly-fitting cover is essential as this species can climb glass, and regular water changes are necessary while allowing aufwuchs to grow on various surfaces.

Behaviour

This species of loach is delicate and should not be housed with aggressive or dominant tankmates, particularly avoiding Beaufortia, Pseudogastromyzon, or Sewellia species. H. humilis is known to form loose aggregations in nature and can coexist well with specific tankmates like members of Gastromyzon, Sinogastromyzon, Protomyzon, Erromyzon, riverine gobies such as Stiphodon or Sicyopus species, and diminutive cyprinids like Microdevario, Tanichthys, and small Danio species.

Feeding and Diet

In their natural habitat, H. humilis feeds on benthic algae and associated microorganisms by rasping them from solid surfaces. In captivity, they will accept high-quality dried foods, live or frozen bloodworms, and homemade foods rich in fresh vegetables and Spirulina. Maintaining an aquarium with ample algae-covered rocks and surfaces is crucial for their long-term health. If algae growth in the main tank is insufficient, a separate tank for growing algae may be required.

Reproduction & Dimorphism

Information on the reproduction of Hypergastromyzon humilis is unrecorded. The sexual dimorphism in this species is noticeable based on the head and body shape when viewed from above or below. Females tend to have a heavier frame with a more continuous snout-to-pectoral fin connection, while males are slender with a squarer snout shape and pectoral fins emerging at a different angle.

Habitat and Distribution

H. humilis is exclusively found in the Sungai Melawi river basin within the Kapuas system in Kalimantan Barat, Indonesian Borneo. These loaches inhabit swift, shallow forest streams with clear, oxygen-rich water, commonly residing in runs and riffles. The substrate typically consists of gravel, rocks, or boulders covered in biofilm, and aquatic plants are scarce in their habitat. They cohabit with other endemic species like Gastromyzon contractus, G. ridens, and G. praestans in the Melawi drainage area.