Corydoras catfish

Appearance

This fish is known by many different names: Cory Cats, Cory Catfish, Cory fish or simply Corydoras. They are a popular bottom dwelling catlike fish. Corydoras catfish are well-known for their vibrant colors and unique patterns. They have a long, sleek body with a distinct dorsal fin and a forked tail. They have whiskers, just like cats, but these are in fact barbels, which help them in detecting food. They are typically small fish with a maximum size of around 4 to 10 cm (2 – 4 inches).

There are multiple species of Corydoras, for example Corydoras aeneus, which is known for its metallic green or bronze coloration with dark spots or lines on its body. It is probably the most common species kept in home aquariums. Other Corydoras catfish species are Corydoras paleatus, which have a silver body with black spots, or Corydoras julii, which have black and white banding on its body. It’s worth to mention that there are over 170 species of Corydoras catfish and they come in different sizes, colors, and patterns.

Natural environment

Corydoras catfish are native to South America and found in a variety of freshwater environments, including rivers, streams, and tributaries. They prefer slow-moving or still water, such as swamps, ponds, and backwaters. They can also be found in these habitats’ sandy and muddy bottoms, where they can search for food. They are usually found in relatively warm water, with temperatures ranging from 22 to 25 °C (72 – 78 °F). Corydoras prefer a pH range of 6.5 – 7.0, but can tolerate up to 8.0. Corydoras catfish’s natural environment is characterized by abundant vegetation and hiding places, such as rocks and wood, which provide cover and protection from predators.

Behaviour

Corydoras catfish are known for their peaceful and active behavior. They are a schooling fish, and they prefer to live in groups of at least six individuals. In the wild, they are often found in large schools, which can number in the hundreds. In captivity, they will often form loose schools and can be observed swimming and exploring their environment together. They are also known to be active during the day and night, so they can be observed in the aquarium at any time.

Corydoras catfish are also known for their bottom-dwelling behavior, where they forage for food along the substrate. They use their barbels to help them locate food, and they will often be seen sifting through the substrate for bits of leftovers. They are also known to be very curious fish, as they will often investigate new objects or changes in their environment.

Corydoras catfish are hardy fish, which makes them easy to care for in captivity. They are able to adapt to a wide range of water conditions, but it is important to do regular water changes, as Cory Cats do not do well in tanks with high nitrates (NO³) levels: it stresses them out, compromising their immune system, making them more susceptible to catch diseases.

Small catfish Corydoras frontal closeup with blurred background. Selective focus.

Reproduction & life span

Corydoras catfish reproduce through eggs that are laid on plants or other surfaces in the aquarium. They can be bred in captivity, but it can be difficult to achieve. Unlike many other species, they don’t have a set breeding season and they don’t have any obvious physical characteristics that indicate they are ready to breed. The best way to encourage breeding is to provide optimal water conditions (eSHa OPTIMA), a varied diet and by keeping a group of at least 6 individuals.

The eggs are usually laid in batches, and the females will lay several batches throughout the breeding season. After the eggs are laid, they will hatch within 3 – 5 days, depending on the temperature of the water. Once the fry are hatched, they are free-swimming and will consume small foods such as infusoria, baby brine shrimp and powder food.

Corydoras catfish have a lifespan of about 5 – 10 years in captivity when kept under optimal conditions. They are known for their hardy nature, but proper care and maintenance are still important to ensure they live a long and healthy life. Regular water changes, proper filtration, and regular testing of water parameters are all crucial to the health and well-being of these fish. Additionally, Corydoras catfish are sensitive to changes in water chemistry and should be introduced to the aquarium gradually.

Diet

In the wild Corydoras feed on a variety of small aquatic invertebrates, such as worms, crustaceans, and insect larvae. They are omnivorous, which means that they will accept a variety of different food types. In an aquarium they will consume a wide range of live, frozen and dry foods such as brine shrimp, daphnia, blood worms and flake food. They also require a diet that is high in vegetable matter such as fresh vegetables and algae. Make sure to additionally feed them with specially designed tablets for Cory Cats.

Keeping a Corydoras catfish

It’s important to provide Corydoras catfish with the right conditions to thrive. The first thing to consider when keeping them is the tank size. These fish are active and need enough space to swim and explore. A group of at least 6 individuals should be kept in an aquarium with a capacity of 50 liters (13 gallons) or more. This will give them enough room to move around and will also help to reduce stress and aggression.

Water temperature is another important factor to consider when keeping a Corydoras catfish. They are tropical fish and require warm water to thrive. The ideal water temperature for these fish is between 20 and 26 °C (68 and 79°F). It’s important to maintain this temperature range to ensure the health and well-being of your fish.

Water chemistry is also crucial for the health of your Corydoras catfish. They prefer a neutral to slightly acidic pH range, typically between 6.5 – 8.0. It’s important to regularly test the water parameters and make any necessary adjustments to maintain the ideal water chemistry.

Proper filtration is also essential for the health of your Corydoras catfish. A high-quality filtration system will help to keep the water clean and clear, which is important for their overall well-being. Lighting is another important factor to consider, they prefer low to moderate lighting, so a low-wattage bulb or LED light works best.

A sandy substrate of at least 5 cm is best for these fish as they like to burrow and forage for food along the bottom. They love plants, rocks and decorations to explore and use as a hiding place. Cory cats can speed up to the surface from time to time for food or to grasp some air. Therefore it’s important to have a tightly lit aquarium. They are omnivorous and will accept a variety of live, frozen, and dry foods such as brine shrimp, daphnia, blood worms, and flake food.

Fish. Corydoras julii in aquarium. Corydoras trilineatus