Black fin cory - Corydoras leucomelas

Scientific name: Corydoras leucomelas

Common name: Black fin cory

Family: Callichthyidae

Usual size in fish tanks: 4 - 5 cm (1.57 - 1.97 inch)

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Recommended pH range for the species: 6.8 - 7.5

Recommended water hardness (dGH): 8 - 20°N (142.86 - 357.14ppm)

0°C 32°F30°C 86°F

Recommended temperature: 22 - 27 °C (71.6 - 80.6°F)

The way how these fish reproduce: Spawning

Where the species comes from: South America

Temperament to its own species: peaceful

Temperament toward other fish species: peaceful

Usual place in the tank: Bottom levels

Food and Feeding

The Black Fin Cory (Corydoras leucomelas) is an omnivorous bottom-dweller that enjoys a varied diet. Their staple diet can consist of high-quality sinking pellets or flakes, specifically formulated for bottom-feeding fish. Once or twice a week, provide protein-rich treats like bloodworms or brine shrimp to enhance their health and stimulate natural feeding behaviors. Additionally, they may nibble on algae wafers or blanched vegetables like spinach or zucchini, which add variety to their diet. For variety, you may also offer occasional treats like micro-pellets, crushed freeze-dried foods, and tubifex worms, which add different textures and nutrients to their diet. Ensuring a balanced and varied diet will support their immune health and vibrant appearance.

Origin

The Black Fin Cory originates from the rivers and streams of South America, particularly in Colombia and Peru. These fish inhabit slow-moving or still waters with soft, sandy substrates where they can forage for food. In the wild, they thrive in shaded areas with plenty of leaf litter and plant cover.

Sexing

Distinguishing between male and female Black Fin Corys is easiest when viewing them from above. Females are generally rounder and broader-bodied, especially noticeable when they are full of eggs. Males tend to be slimmer and more streamlined.

Breeding

Breeding Corydoras leucomelas in captivity can be achieved by setting up a peaceful, well-maintained environment. They will breed in groups or as a bonded pair. To encourage spawning, perform daily water changes with slightly cooler water, which mimics rainfall and signals breeding conditions. Females typically deposit their eggs on tank glass, plants, or other surfaces. The eggs hatch in 3-4 days, and the free-swimming fry can be fed infusoria or rotifers. As they grow, transition to larger foods like microworms and newly hatched brine shrimp.

Lifespan

With proper care, the Black Fin Cory can live for 5 years or more. Maintaining stable water conditions, a balanced diet, and a peaceful environment contributes to their longevity.

Tank Requirements

Black Fin Corys thrive in well-maintained aquariums with a fine sandy substrate, which is gentle on their delicate barbels. A tank of at least 40 liters (~10 gallons) is recommended for a small group, but a larger tank of 76 liters (~20 gallons) or more is preferable for keeping a school of six or more, allowing them to display natural behaviors. Ensure the tank includes moderate to low lighting, as Corydoras prefer shaded areas, and add driftwood, smooth rocks, and leaf litter to replicate their natural habitat.

To maintain suitable water conditions, keep the temperature between 22-27°C (71.6-80.6°F), pH within 6.8-7.5, and water hardness between 8-20°N. A gentle filtration system is best to avoid creating a strong current, as Corydoras are not strong swimmers. Weekly water changes are recommended to maintain high water quality. Regular substrate maintenance is important to prevent the buildup of waste, which can harm Corydoras. Gently vacuum the substrate during water changes to remove uneaten food and debris, taking care not to disrupt their habitat too much, as they rely on the substrate for natural behaviors like foraging and burrowing.

Behavior

Black Fin Corys are active during the day and enjoy social interactions within their group. They often engage in synchronized swimming and foraging behaviors along the substrate. Observing them in groups reveals their gentle nature and social dynamics, which is why keeping them in schools enhances their comfort and reduces stress.

Recommended Tankmates

The peaceful Black Fin Cory is best kept with similarly sized, non-aggressive species. Ideal tankmates include:

Characins, such as Black Neon Tetras and Rummy Nose Tetras
Small, peaceful cyprinids like Harlequin Rasboras or Zebra Danios
Other Corydoras species
Dwarf cichlids, such as Apistogramma or German Blue Rams
Peaceful livebearers, like Guppies or Endler’s Livebearers

Avoid aggressive or large predatory fish, as they may stress or harm Corydoras. Black Fin Corys are generally compatible with small invertebrates like snails and certain species of freshwater shrimp, such as Amano or Cherry shrimp, which can add diversity and assist with natural cleaning processes.

Recommended Plants

Live plants help create a natural environment and provide shade for Black Fin Corys. Suitable plant choices include:

Java Fern (Microsorum pteropus)
Anubias (Anubias barteri)
Amazon Sword (Echinodorus amazonicus)
Water Wisteria (Hygrophila difformis)
Java Moss (Vesicularia dubyana)

These plants tolerate low to moderate light and provide plenty of hiding spaces for the Corydoras. They also contribute to water quality by absorbing nitrates and adding oxygen to the tank.

Short Description

The Black Fin Cory (Corydoras leucomelas) is a hardy, peaceful bottom-dweller known for its unique black dorsal fin and distinctive markings. Originating from the rivers of South America, these fish thrive in soft, sandy substrates with ample cover. They should always be kept in groups of at least six, as they are social and enjoy the company of their own species. Their compatibility with other peaceful tankmates makes them an excellent choice for community aquariums. With their easygoing nature and adaptability, Black Fin Corys are well-suited for both novice and experienced aquarists.