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Butterfly Hillstream Loach
Beaufortia kweichowensis
The Chinese Hillstream Loach is a unique, flat-bodied fish adapted to fast-flowing streams. It thrives in highly oxygenated river manifold setups, grazing on algae and biofilm.
Water Temperature
18 - 24 °C
pH Value
6.5 - 7.5
Water type
Freshwater
Tank level
Bottom and middle
Adult size
8 cm
Minimum tank volume
>= 100 L
Minimum group
>= 1
GH
4 - 12 dGH
KH
2 - 6 dKH
TDS
80 - 240 ppm
Conductivity
125 - 375 uS/cm
Species description
Geographical Origin and Habitat: Native to the Xi Jiang river basin in southern China. Inhabits exclusively fast-flowing, cold and highly oxygenated mountain streams, clinging firmly to smooth boulders in the current.
Taxonomy and Morphology: Chinese Hillstream Loach / Butterfly Pleco (Beaufortia kweichowensis). Often sold as a "pleco" or "freshwater stingray", it is actually a loach. The body is extremely flattened and the pectoral and pelvic fins form an integral elliptical suction cup to resist the current.
Social Behavior: Territorial towards conspecifics in tight spaces, but the "fights" are harmless dances in which two individuals push each other laterally ("parallel swimming"). Totally peaceful and harmless towards any other fish species.
Coloration and Sexual Dimorphism: Pale beige/golden background with an intricate pattern of blackish spots and reticulations (leopard type) extending over the entire "fan" body. Difficult to sex, but adult females seen from above are slightly thicker and less angular than males.
Care, breeding and tankmates
Aquarium Setup: "River Manifold" tank essential (min. 80 cm / 32 inches). The layout must include rounded and smooth river pebbles, very strong lighting to promote algae growth, and powerful unidirectional movement pumps (15-20 times the volume).
Diet and Feeding: Aufwuchs scraper. Survives by scraping biofilm, flat algae and microorganisms from stones. The aquarium MUST be mature and full of green algae on the stones. Accepts flaked spirulina tablets and vegetable gel, but never touches plants.
Water Quality: Cool water sub-tropical species (18-24°C / 64-75°F). The heater is not needed or is harmful. The water must be brutally oxygenated: a decrease in oxygen or a summer thermal peak above 26°C (79°F) kills them by asphyxiation.
Compatibility and Cohabitation: Perfect with other Hillstream species (Sewellia, Gastromyzon), Danio rerio, Tanichthys albonubes and small stream gobies (Rhinogobius). Incompatible with classic tropical fish that require still and warm waters.
Aquarium Breeding: Extremely rare. They lay eggs in excavations among the bottom pebbles in areas with strong current. The fry hide in the substrate feeding on micro-algae and infusoria before emerging.
Risks and Diseases: Starvation from "clean aquarium". They literally starve to death in classic warm, clean tropical community aquariums maniacally scraped by the aquarist. Green algae stones are their life insurance.
Geographic Origin and Distribution
Native to the Xi Jiang river basin in southern China. Inhabits exclusively fast-flowing, cold and highly oxygenated mountain streams, clinging firmly to smooth boulders in the current.
Origin
Tropical oceans and reefsEast Asia
Fish profile
- Temperament
- Semi-aggressive
- Butterfly Hillstream Loaches are generally peaceful and make excellent community fish, though they show interesting territorial behaviors. Males will actively defend their favored algae-grazing spots from other males by pushing and hovering over each other, but these interactions are harmless and do not result in injury. Females are much more social and tend to congregate peacefully in calmer areas of high flow.
- Diet
- Omnivore
- In nature, these fish feed primarily on aufwuchs, which is a complex matrix of algae, diatoms, and microorganisms growing on rocks. In the aquarium, they require a mature setup with a steady supply of natural algae. Their diet should be supplemented with high-quality sinking wafers, spirulina tablets, and occasional meaty foods like frozen bloodworms or brine shrimp, though excessive protein must be avoided.
- Life expectancy
- 5-8 years
- With proper care, a suitable cold-water environment, and a consistent supply of food, Butterfly Hillstream Loaches can live for 5 to 8 years in captivity. Their lifespan is highly dependent on water temperature and oxygen levels. Maintaining cooler temperatures and ensuring the water is highly oxygenated are crucial for their long-term health and survival.
- Adult size
- 8 cm
- The catalog's scalar value is 8 cm. The FishBase SPECIES table (v25.04 snapshot) source reports a maximum adult measurement of 8 cm for this species, recorded as total length (TL). The taxonomic record consulted is Beaufortia kweichowensis (v25.04); male or unsexed record. These figures are not interchangeable: the first is the profile's editorial reference, whereas the second is a published maximum under a specific measurement convention; differences among sources can reflect sex, population, life stage and measuring method.
- Sex ratio
- Group
- In their natural habitat, Butterfly Hillstream Loaches live in loose aggregations, and it is recommended to keep them in groups of six or more. Keeping them in larger groups allows them to exhibit their natural, active behaviors and reduces stress. While males are territorial and will engage in harmless squabbles over prime feeding spots, they do not cause injury to one another.
- Feeding frequency
- Twice daily
- Because their diet relies heavily on continuous grazing of biofilm and algae, they should have access to algae-covered surfaces at all times. Supplemental feedings of dry or frozen foods can be offered once or twice daily in small amounts. It is crucial to ensure that other tankmates do not outcompete them for these supplemental foods, especially during their initial acclimation period.
- Bioload
- Low
- Despite their small size, Butterfly Hillstream Loaches require extremely clean, highly oxygenated water with strong currents. They do not produce a high amount of physical waste, but they are very sensitive to organic pollutants and high nitrates. To maintain pristine water quality, an oversized filter with a turnover rate of 10-15 times the tank volume per hour is strongly recommended.
- Flow
- Stagnant
- These loaches are obligate stream dwellers that require strong water flow and high turnover rates in the aquarium. A turnover rate of at least 10 to 15 times the tank volume per hour is ideal to simulate their fast-flowing wild habitats. The use of additional powerheads and airstones is highly recommended to maintain maximum oxygen levels and water movement.
- Jump risk
- Yes
- Although they lack the ability to jump in the traditional sense, Butterfly Hillstream Loaches are skilled climbers that can easily scale the glass sides of a tank. Because of this unique behavior, they can crawl out of the aquarium if there are open gaps. A tight-fitting lid or cover slides are absolutely essential to prevent them from escaping and drying out.
- Reproduction
- Oviparous
- Breeding the Butterfly Hillstream Loach in captivity is considered extremely difficult, and there are very few documented cases of successful spawning in home aquaria. In their natural environment, they are believed to be seasonal spawners that lay eggs in gravel crevices. Replicating the precise changes in water temperature, flow, and food availability required to trigger spawning remains a significant challenge for aquarists.
- Compatibility & tankmates
- They are peaceful fish but require tankmates that thrive in the same specialized conditions of cool water and strong current. Suitable companions include other hillstream loaches, temperate gobies like Stiphodon or Rhinogobius, and active schoolers such as Devario or Danio species. They should not be kept with slow-moving or warm-water species, and they are generally poor tankmates for fancy goldfish due to different care requirements.
- Tank level
- Middle/Bottom
- These loaches possess specialized, flattened bodies with fused pelvic fins that act as a suction cup, allowing them to cling to smooth rocks and glass. Consequently, they do not swim in open water but instead crawl along the bottom and lower-to-middle sides of the aquarium. They prefer environments with plenty of flat river stones, where they spend most of their time grazing on biofilm.
Scientific Parameters & Models
FishBase
Window to the official scientific data of the species
Data synced on: 06/15/2026
- Trophic level
- 2.7 ± 0.2 se
- Phylogenetic uniqueness (PD50)
- 0.5001
- Bayesian Length-Weight
- a = 0.00891, b = 3.06
- VulnerabilityLow vulnerability (10 / 100)
Image gallery
Licensed images linked to the species or, when marked, to the closest representative taxon.
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