Macropterus Cory
Scleromystax macropterus
Very rare species. Adult males develop disproportionately long and flowing dorsal and pectoral fins (macropterus = large fins), which they exhibit in vigorous bloodless territorial fights.
Water Temperature
18 - 23 °C
pH Value
6 - 7.2
Water type
Freshwater
Tank level
Bottom
Adult size
8.5 cm
Minimum tank volume
>= 100 L
Minimum group
>= 6
GH
2 - 12 dGH
KH
3 - 10 dKH
TDS
60 - 280 ppm
Conductivity
94 - 438 uS/cm
Species description
Geographical Origin and Habitat: Sub-tropical species endemic to the southern Atlantic coastal basins in Brazil. Populates hilly rivers characterized by rapid currents, light pebbly bottoms, and very clear waters lashed by very cold temperate winds in winter.
Taxonomy and Morphology: Majestic siluriform separated from the Corydoras genus due to morphological divergences. "Macropterus" designates the absurd and gigantic "mantle" development of the male dorsal and pectoral fins. Very robust species that touches 8.5 - 9 cm (3.3-3.5 inches).
Social Behavior: Discreet territoriality among dominant males combined with the intrinsic need for a school: set up tanks for schools of 6-8 individuals. Less frantic in continuous rooting compared to Corydoras; prouder, more isolated, and meditated swimming.
Coloration and Sexual Dimorphism: Stunning sexual dimorphism. Breathtaking male, with a dark brown livery crossed by a bright yellow-gold ribbon, with an immense dorsal fin that touches the caudal and opercular "beard". The female is stocky, modestly spotted, and with very short fins.
Care, breeding and tankmates
Aquarium Setup: Spacious tanks for adult males, set up to simulate the sub-tropical stream: mixed fine sand/rounded river pebbles, massive smooth stones covered by a lively and prolonged current (essential movement pumps to emulate the habitat).
Diet and Feeding: Grain size and volumes must fulfill its great carnivorous-omnivorous needs: robust compressed tablets (bottom wafers) must stably alternate with generous protein injections of giant bloodworms, shelled shrimp, and mysis.
Water Quality: THE FISH DIES IF HOUSED AT CLASSIC TROPICAL TEMPERATURES. The water must NEVER exceed 23-24°C (73-75°F), preferring cold winter bands between 18-22°C (64-72°F). Requires monstrous oxygenation. Slightly acidic or neutral pH (6.0 - 7.2) and mild GH (2-12).
Compatibility and Cohabitation: Excellent for tanks dedicated to Hillstream loaches and subtropical species of moving water, or Danios and White Cloud Mountain Minnows. Lethal and incompatible insertion in warm discus tanks, or with Asian Loaches that would nibble its fabulous nuptial drapes.
Aquarium Breeding: Males exhibit bloody dominance rituals by opening their fleshy lobes (beard). The female attaches a few dozen large leathery eggs in turbulent corners on plastic surfaces or smooth stones. Move the parents or the eggs given the unstoppable gluttony.
Risks and Diseases: If the aquarium travels at a constant 26°C (79°F), the fish is subject to lightning-fast immunological decline and unstoppable bacterial breakouts. The wear on the barbels on sharp bottoms is deadly; hypersensitive to Copper and Malachite green.
Geographic Origin and Distribution
Sub-tropical species endemic to the southern Atlantic coastal basins in Brazil. Populates hilly rivers characterized by rapid currents, light pebbly bottoms, and very clear waters lashed by very cold temperate winds in winter.
Origin
Tropical oceans and reefsExtra-Amazon South America
Fish profile
- Temperament
- Semi-aggressive
- They are gregarious, peaceful, and somewhat shy when kept singly. They gain confidence when kept in groups of at least six individuals. Providing dim lighting and plenty of cover helps them feel secure and encourages natural behaviors.
- Diet
- Omnivore
- Their diet consists of sinking omnivore preparations and meaty foods. They eagerly consume sinking pellets, algae wafers, and frozen or live bloodworms and daphnia. Providing a varied diet is crucial for conditioning them for breeding.
- Life expectancy
- 8-10 years
- In captivity, Scleromystax macropterus typically lives for 8 to 10 years when housed in high-quality, subtropical water conditions. They are sensitive to high temperatures, and maintaining them in water that is too warm will accelerate their metabolism and shorten their life. Proper care, including regular maintenance and the use of sand to protect their delicate barbels, is essential for a long life.
- Adult size
- 8.5 cm
- The catalog's scalar value is 8.5 cm. The FishBase SPECIES table (v25.04 snapshot) source reports a maximum adult measurement of 8.7 cm for this species, recorded as standard length (SL). The taxonomic record consulted is Scleromystax macropterus (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
- A ratio of multiple males per female is often recommended to encourage successful spawning. Males can develop striking elongated fins and may display to one another without causing harm. Keeping them in groups of six or more provides the best social dynamic.
- Feeding frequency
- Twice daily
- Feeding them one to two times daily is sufficient for their nutritional needs. Ensure that other tank mates do not consume all the food before it reaches the bottom. Uneaten food should be removed promptly to maintain pristine water conditions.
- Bioload
- The bioload produced by this fish is considered light to moderate. As a smaller bottom-dwelling species, they do not generate excessive waste. Standard biological filtration combined with routine maintenance easily handles their output.
- Flow
- Stagnant
- They enjoy moderate to moderately strong water currents mimicking their native streams. Good water movement ensures adequate oxygenation, which is essential for their well-being. Using a spray bar can help distribute the flow evenly across the tank.
- Reproduction
- Oviparous
- Breeding this species requires cooler water temperatures, simulating the rainy season. Females attach sticky eggs to solid surfaces like plants or the aquarium glass. The parents exhibit no parental care and will consume the eggs if left in the breeding tank.
- Compatibility & tankmates
- They are exceptionally peaceful and thrive in a peaceful community setup. Ideal tank mates include small tetras, rasboras, and calm dwarf cichlids. They should never be housed with large or aggressive species that may harass or eat them.
- Tank level
- Bottom
- They are bottom-level dwellers that interact intimately with the substrate. They constantly sift through sand looking for morsels of food. It is vital to use smooth sand or fine gravel to prevent injury to their sensitive sensory barbels.
Scientific Parameters & Models
FishBase
Window to the official scientific data of the species
Data synced on: 06/15/2026
- Trophic level
- 2.9 ± 0.3 se
- Resilience
- High (less than 15 months)
- Phylogenetic uniqueness (PD50)
- 0.5078
- Bayesian Length-Weight
- a = 0.00741, b = 3.14
- VulnerabilityLow vulnerability (10 / 100)
Image gallery
Licensed images linked to the species or, when marked, to the closest representative taxon.
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Recommendations grouped by close relatives, companion choices, and similar care.
