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Gastromyzon lepidogaster

Gastromyzon lepidogaster

Fishes › Carp, barbs, minnows, loaches (Cypriniformes) › Gastromyzontidae (Hillstream loaches)

Gastromyzon lepidogaster is a species of river loach (family Balitoridae or Gastromyzontidae, depending on the source).

Aquarium hobby
Experience: Intermediate
Gastromyzon lepidogaster
Photo: (c) Dan L., some rights reserved (CC BY), CC BY 4.0, via iNaturalist
FamilyHillstream loaches
Adult lengthup to 4 in
WaterFreshwater

Care at a glance

Species-specific aquarium care

  • Tank: At least 24 in long and 12 in front to back for one adult (adults commonly reach about 4.0 in / 10.15 cm).
  • Water: Freshwater.
  • Layout: Uses both the bottom and open water: give open swimming space plus cover near the substrate.
  • Availability: Rarely or never seen in the aquarium trade; expect to source it from specialists or not at all.

Calculated from this species' own FishBase record: tank size from its typical adult length and swimming zone, water values from its recorded ranges. The group guide below fills in general care.

Care guide

Species care notes

  • Tank: a base of at least 47 × 12 in (roughly 29 US gallons); space needed is rated “large tank”.
  • Water: a fairly wide range, from slightly acidic to slightly alkaline, 64–75 °F, pH 6–8.5, 2–12 dGH.
  • Behaviour: temperament peaceful; a shoaling fish best kept in a group of six or more; not a community fish.
  • Difficulty: Moderate (Seriously Fish rating).

Short excerpts from the species profile:

  • Setup: “Most importantly the water must be clean and well-oxygenated so we suggest the use of an over-sized filter as a minimum requirement.”
  • Diet: “Much of the natural diet is likely to be composed of benthic algae plus associated micro-organisms which are rasped from solid surfaces.”
  • Tankmates: “Very peaceful although its environmental requirements limit the selection of suitable tankmates somewhat, plus it should not be housed with any much larger, more aggressive, territorial or otherwise competitive fishes.”
  • Breeding: “Has not been bred in aquaria and the only observations we know of for any member of the genus were made by German aquarist Philipp Dickmann and published in a hobbyist magazine during 2001.”

From the Seriously Fish profile for this species, which has the full habitat, maintenance, diet, behaviour and breeding write-up 167

Group care guide

Hillstream loaches

Applies to most species in this group. Habitat: Balitora inhabit fast-flowing Asian hillstream riffles with rocky beds and abundant dissolved oxygen. [fg177-bal]. Individual species can differ, so compare with the species numbers above and the linked sources.

The water range is for B. brucei, not a verified range for every Balitora. Species-specific captive data for B. annamitica, B. burmanica, B. chipkali, B. eddsi, B. elongata, B. haithanhi and B. jalpalli are not supplied by these references. Older hillstream literature uses Balitoridae broadly and includes genera now placed elsewhere; its feeding and social observations must not be treated as equally proven for every current balitorid. Level 4 is an editorial assessment of specialized flow and oxygen requirements. [fg177-bal, fg177-river]

Housing & setup

  • Use a long river aquarium; the river-tank reference recommends at least 3 feet of length, rather than a species-tested minimum.
  • Provide strong directional current and vigorous aeration throughout the occupied area.
  • Supply smooth pebbles, boulders and numerous rocky refuges out of the main current.
  • Use bright lighting and an established aquarium with grazing growth on rocks.
  • For B. brucei, maintain pH 7.0–8.0 and medium hardness up to 12 dGH.

Sources 938939940

Climate & lighting

Water68–75°F

Sources 938939940

Diet

  • Algae and established rock biofilm.
  • Frozen bloodworms and mysis shrimp.
  • Pelleted foods.

Sources 938939940

Social life

  • Provide separate resting and feeding surfaces; hillstream keepers report competition for favored rocks, but a Balitora-specific group size is not established here.

Sources 938939940

Health watch

  • Oxygen deprivation, especially during overheating or inadequate aeration.
  • Poor condition from inadequate access to established grazing growth.
  • Skin disease with patchy coloration and loss of appetite; obtain a diagnosis rather than treating by appearance alone.

Sources 938939940

Understanding the animal

This species is part of a group that hobbyists, aviculturists or zoos keep widely (Hillstream loaches), so it's included for completeness. It may be rare in captivity itself, or not kept at all. Use the group guide as a starting point and look for species-specific advice from experienced keepers.
About this animal

About this animal

It is endemic to northern Borneo. It inhabits riffles and grows to 10.2 cm (4.0 in) standard length.

Quoted from the Wikipedia article “Gastromyzon lepidogaster” (CC BY-SA 4.0) 174

In the wild

In the wild

From this species’ own FishBase record (habitat, bottom type, water and breeding data), not its family. Good care copies these conditions.1

Where it livesLives in freshwater. Uses both the bottom and open water.
Water it lives inFreshwater.
ClimateTropical climate.
  1. FishBase species summary: Gastromyzon lepidogaster
Native climate (measured)

Native climate (measured)

Warm-season highsabout 86°F (up to 88°F in the hottest sampled areas)
Cool-season lowsabout 71°F (down to 65°F in the coldest sampled areas)
Average temperature72–79°F across sampled records
Relative humidity79–82% on average (driest month about 76%)
Rainfallabout 2442 mm a year, spread fairly evenly

Measured at 19 wild occurrence records sampled against WorldClim 2.1 climate data (1970–2000 averages). Air conditions in the range are ecological context, not enclosure settings: microhabitats such as burrows, leaf litter or basking rocks can be cooler, warmer or more humid.

From the sources

From the sources

Quoted from the matching sections of reputable sources for this exact species. Specialist databases are used first; Wikipedia (community-edited, CC BY-SA 4.0) only fills gaps. Other sources are short credited quotes.

Where it livesHome ranges Population dynamics Growth parameters Max. ages / sizes Length-weight rel. Length-frequencies Mass conversion Recruitment Abundance Life cycle Reproduction Maturity Maturity/Gills rel. — FishBase

Data and studies

The numbers

The numbers

Each bar is what one source reports. Where several sources weigh in, the dashed gold band marks their average.

Adult length

Average of sources4in
FishBase 1644
Seriously Fish species profiles 1673.9

Maximum recorded length. Measured as standard length (snout to the base of the tail, not counting the tail fin). Fish in home aquariums often stay smaller than wild records.

Water temperature

Reported64–75°F
Seriously Fish species profiles 16764–75

Range the species tolerates; aim for the middle.

pH

Reported6–8.5
Seriously Fish species profiles 1676–8.5

Water hardness

Reported2–12dGH
Seriously Fish species profiles 1672–12

Minimum tank footprint

Reported47in
Seriously Fish species profiles 16747

Seriously Fish recommends a tank base of at least 47 × 12 in (about 29 US gallons).

Sources for this sheet

  1. FishBase (Froese & Pauly, eds.), version 24.07 Peer-reviewed researchThe global scientific database on fishes, maintained by a consortium of research institutions; every value is referenced.
  2. Seriously Fish species profiles Experienced keeper or breederLong-running aquarium reference written and peer-checked by experienced fishkeepers and ichthyologists; each profile covers habitat, tank size, water, diet, behaviour and breeding.
  3. Loaches Online: Balitora brucei Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
  4. Loaches Online: Hillstream Loaches — The Specialists at Life In The Fast Lane Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
  5. Merck Veterinary Manual: Disorders and Diseases of Fish Zoo, university or veterinaryAdded in the 2026 source-checked care-guide review.
  6. Wikipedia (species article) Community referenceFree encyclopedia; useful overviews with their own citations. Intro text is quoted under CC BY-SA 4.0.
  7. iNaturalist (captive observations) Community referenceCommunity observation platform run by the California Academy of Sciences and National Geographic; observations marked captive show animals living in homes, zoos and aquariums.