Corydoras Catfish – Corydoras spp.

Corydoras catfish belong to one of the most popular groups of bottom-dwelling fish in home aquariums. Peaceful, active and extremely useful as a clean-up crew, they win the hearts of both beginners and advanced aquarists. In this article we will look at their natural behaviour, requirements and breeding, so you can provide them with optimal conditions in your tank. At MB Store you will find suitable aquariums, filtration systems and other equipment that will help you create a safe environment for these fascinating fish.

Natural habitat and behaviour of Corydoras catfish

Corydoras catfish come from South America, where they inhabit slow-flowing rivers, floodplains and forest streams. In nature they are usually found near the bottom, among roots, fallen leaves and fine sand. Their bodies are covered with bony plates instead of typical fish scales, which act as a natural armour. This adaptation helps them survive in waters where predators and sharp objects are common.

These fish are classic schooling species. In the wild they live in groups that can reach dozens or even hundreds of individuals. In the aquarium they should always be kept in a group of at least six fish of one species, although larger groups are even better. In such conditions they show natural behaviours: group foraging, synchronous swimming and the characteristic “wiggling” movements of the whole shoal along the bottom.

Corydoras are most active during the day and early evening. They diligently search the substrate with their sensitive barbels, looking for food particles. Contrary to a common myth, they do not feed on fish waste; they need a normal, well-balanced diet just like other fish. Their peaceful nature makes them perfect tankmates for many community setups, provided that other fish are not aggressive or overly large.

In their natural habitat, Corydoras often inhabit slightly shaded waters with a large amount of organic matter. Leaves, branches and roots create a complex structure at the bottom, providing hiding places and surfaces for biofilm to grow on, which is an additional source of food. Recreating at least part of these conditions in the aquarium will significantly improve the health and well-being of your fish.

Aquarium size and equipment for keeping Corydoras

When planning an aquarium for Corydoras catfish, the base dimensions and bottom area are more important than the height of the tank. These fish live near the substrate, so a low but wide aquarium can be more suitable than a tall, narrow one. For a small group of Corydoras, an aquarium of about 60 cm in length is the minimum, but a larger footprint is always beneficial. MB Store offers a wide range of aquariums and matching stands, allowing you to select a tank that provides ample bottom space.

The filtration system should ensure stable water parameters and gentle water movement. Corydoras come from relatively calm waters, so excessively strong currents can cause stress and fatigue. A good-quality internal or external filter with adjustable flow is recommended. In MB Store you will find filters adapted to tanks of various sizes, as well as filter media that help maintain water clarity and biological balance.

Heating is another important element of equipment. Most Corydoras species feel comfortable in temperatures between 22 and 26°C, although some species prefer slightly cooler or warmer water. A reliable and properly sized heater with a thermostat will keep the temperature stable, which is especially important during seasonal changes in room temperature.

An aquarium lid or cover is highly recommended. Although Corydoras are not known as jumpers, startled fish may occasionally dash upwards and jump out of an open tank. Adequate lighting should not be overly intense; moderate light, often softened by floating plants, best reflects their natural conditions and helps them feel secure.

Do not forget about aeration, especially in heavily stocked or warm tanks where the dissolved oxygen level can drop. An air pump and air stone will increase gas exchange at the water surface. While Corydoras can breathe atmospheric air thanks to their specialised intestine, they should never be forced to rely on this adaptation due to low oxygen levels in the water.

Substrate and decorations – creating a safe bottom zone

The choice of substrate is one of the most critical decisions when keeping Corydoras. Their barbels are very delicate and can be easily damaged by sharp gravel. A soft, fine sand is considered the best option. It allows the fish to dig and sift the substrate naturally, searching for food without risk of injury. If you choose fine rounded gravel, make sure it is not sharp and regularly monitor the condition of the barbels.

Decorations should create a network of hiding spots, caves and shaded areas. Roots, driftwood and rocks with smooth edges can be used to build structures that offer both security and territorial boundaries. Corydoras, although peaceful, appreciate the opportunity to retreat from brighter light or more active tankmates. When arranging decor, leave plenty of open areas of sand where the group can forage together.

Plants complement the visual design and provide functional benefits. Dense vegetation along the back and sides of the aquarium offers cover, while open central spaces remain accessible for group activities. Hardy species such as Java fern, Anubias and various stem plants work well. Floating plants, like Salvinia or Amazon frogbit, help diffuse light and create a more natural atmosphere.

Many aquarists add dried leaves, such as Indian almond or beech leaves, which slowly decompose and create a layer of detritus similar to leaf litter in the wild. They release beneficial tannins, lightly tinting the water and supporting a natural microbiological environment. It is important, however, to control the amount of organic matter to avoid excessive pollution and drops in water quality.

When selecting decorations and equipment, always keep in mind the safety and well-being of bottom-dwelling fish. Avoid sharp edges, poorly finished ornaments and unstable structures that may collapse. Products available at MB Store are carefully chosen for aquarium use, allowing you to create both an aesthetically pleasing and safe environment for your Corydoras.

Water parameters and maintenance routines

Stable and appropriate water parameters are fundamental for the health of Corydoras catfish. Most commonly kept species prefer soft to moderately hard water with a slightly acidic to neutral pH, usually between 6.0 and 7.5. While they can adapt to a range of conditions if acclimated slowly, sudden changes can cause stress, weaken immunity and lead to diseases.

Regular water changes are essential. In a well-stocked community aquarium, replacing 25–40% of the water each week is a good practice. When adding new water, it should be dechlorinated and of similar temperature to the tank water to avoid thermal shock. Many aquarists use water conditioners that neutralise chlorine and chloramine while binding heavy metals; such products are readily available through MB Store.

Filtration and biological balance must be maintained consistently. Over-cleaning filter media can disrupt colonies of beneficial bacteria that process toxic ammonia and nitrite into less harmful nitrate. Instead of rinsing all media at once, gently clean only a portion of it in removed aquarium water during maintenance. Monitor ammonia, nitrite and nitrate levels using test kits to ensure the environment remains safe.

The presence of Corydoras at the bottom may give the impression that they “clean” the tank, but they primarily consume leftover food, not actual dirt. Overfeeding remains one of the biggest threats to water quality. Uneaten food decomposes quickly, producing harmful substances. Feeding measured portions, which are consumed within a few minutes, will maintain the balance between nutrition and cleanliness.

Temperature stability is another crucial factor. Sudden changes of several degrees in a short period can lead to stress and susceptibility to diseases. Heaters, thermometers and controllers available from MB Store help you maintain constant conditions. In warm climates or during summer, controlling overheating may also be necessary, for example by increasing surface agitation or gently cooling the room.

Feeding Corydoras – diet and feeding strategies

Corydoras are omnivorous bottom feeders, which means they accept a wide variety of food, but also have specific needs. A well-balanced diet should combine high-quality sinking pellets or wafers formulated for bottom-dwelling fish with live or frozen foods. Look for foods rich in protein and essential fatty acids, while avoiding excessive amounts of low-value fillers.

Sinking pellets form the basis of the diet, ensuring that each fish can access food directly on the substrate. Supplementation with live or frozen foods such as bloodworms, daphnia, blackworms or brine shrimp provides enrichment and stimulates natural hunting behaviours. These foods should be offered several times per week, depending on the overall feeding plan for the tank.

Many aquarists mistakenly assume that Corydoras can live on leftovers from food given to fish living in higher parts of the tank. In practice this often leads to underfeeding or uneven competition for food. To ensure that bottom-dwelling fish receive adequate portions, feed them after the main feeding of other species, using dedicated sinking food placed in several spots across the bottom.

Vegetable-based components are also beneficial. Some sinking wafers contain spirulina or other plant ingredients that support digestion and immunity. Supplementing the diet with blanched vegetables such as zucchini or peas can be an occasional variation, although these should not form the majority of the Corydoras menu.

Feeding frequency depends on stocking density, temperature and general activity of the fish. Typically, feeding twice a day in small portions works well. Observe your fish: a healthy Corydoras group will actively search the substrate after feeding but should not appear constantly emaciated or, conversely, obese. Balancing energy intake with activity is key to long-term health.

Compatible tankmates and community setups

Peaceful nature and non-aggressive behaviour make Corydoras excellent inhabitants of community aquariums. They coexist well with small, calm fish such as tetras, rasboras, dwarf gourami, smaller livebearers and many other species that do not treat them as food or harassment targets. When selecting tankmates, pay attention primarily to body size and temperament.

Fish that constantly nip fins, chase other inhabitants or aggressively guard territories are not recommended. Corydoras are sensitive to chronic stress, which can manifest as hiding, reduced feeding and even disease. Avoid combining them with large predatory fish that may see them as prey. Although their bony plates offer some protection, they are not invulnerable to attacks.

It is important to remember that Corydoras are schooling fish. A single specimen or pair cannot fully display their natural behaviour and may feel insecure. A larger group not only improves their comfort but also adds visual interest to the aquarium, as a whole shoal moving along the bottom creates dynamic scenes. Different species of Corydoras can often be kept together, though each group should ideally consist of at least six individuals.

When designing a community setup, consider vertical zoning of the tank. Corydoras occupy the bottom, while other species may prefer midwater or surface levels. Proper selection of inhabitants for various “floors” of the aquarium allows better space use and reduces competition for territory. At MB Store you can find tanks and accessories that make it easier to create multi-level, visually attractive aquascapes.

Adding invertebrates such as shrimp or snails is possible, provided you monitor interactions. Adult shrimp are usually safe, although very young shrimp may sometimes be eaten if they venture too close to foraging Corydoras. Snails, on the other hand, are generally ignored and can serve as additional cleaners of algae and leftover food.

Breeding Corydoras in the home aquarium

Breeding Corydoras can be an exciting challenge and a natural step for aquarists who already provide them with stable conditions. Many species will spawn spontaneously if kept in a suitable group, given good food and clean water. Usually a group containing several males and females is needed; females are typically larger and rounder, especially when full of eggs.

To stimulate spawning, aquarists often use a method that imitates the rainy season. This involves performing a larger water change using slightly cooler water than usual, which lowers the temperature by a few degrees. At the same time, rich feeding with live and frozen foods, especially those high in protein, supports the production of eggs and encourages courtship behaviours.

Before spawning, Corydoras display characteristic behaviour: males follow females, nudging them and forming various configurations. During the act itself, the female often assumes the well-known “T-position” with the male. After fertilisation, she deposits adhesive eggs on aquarium glass, plants or decorations. In some cases, as many as several dozen or even more eggs may be laid during one session.

Adult fish, including parents, may eat eggs, so many breeders remove either the adults or the eggs to a separate rearing tank. The water in such a tank should be well-oxygenated and clean, with a gentle filter, often a sponge filter, which is safe for fry. Some aquarists add agents that limit fungal growth on eggs, but this must be done carefully and in appropriate doses.

After hatching, the fry initially consume the contents of their yolk sacs. Once they start swimming freely, they require very fine food: infusoria, specialised fry powders or freshly hatched brine shrimp. With proper nutrition and clean water, young Corydoras grow steadily, and after a few months they begin to resemble miniature versions of adults. Breeding can thus not only be satisfying, but also help maintain healthy, captive-bred populations of these popular fish.

Health, stress signs and common issues

Corydoras are generally hardy fish, but like any aquarium inhabitants they are susceptible to diseases and stress. One of the earliest warning signs is a change in behaviour: fish that usually actively search the bottom suddenly become apathetic, hide constantly or breathe rapidly. Such symptoms often indicate problems with water quality, inappropriate temperature or the presence of aggressive tankmates.

Pay special attention to the condition of the barbels. Shortening, fraying or complete loss of these structures usually means that the substrate is too sharp or contaminated with decaying food and waste. Replacing the substrate with fine sand and improving maintenance routines often allows barbels to regenerate, but prolonged damage can lead to infections.

Corydoras can also suffer from typical freshwater fish diseases such as ich or bacterial infections. Quarantining new fish before introducing them to the main tank greatly reduces the risk of importing pathogens. Avoid sudden radical changes in water chemistry or temperature, as such fluctuations weaken immunity and open the door to illnesses that would otherwise be repelled by a healthy organism.

Over time, chronic exposure to elevated nitrate levels or unsuitable pH may lead to gradual deterioration of health. Regular testing and preventive maintenance are therefore not just routine chores but a basic element of responsible fishkeeping. MB Store offers test kits, conditioners and medications that can support you in caring for the health of your Corydoras and other aquarium inhabitants.

By observing your fish daily and reacting quickly to any disturbing signs, you can prevent many serious problems. Proper environment, suitable diet and compatible tankmates form the foundation on which the long and healthy life of Corydoras in your aquarium is built.

How MB Store supports your Corydoras aquarium

Creating ideal conditions for Corydoras catfish is much easier when you have access to well-selected, proven products. MB Store offers a wide range of aquariums in various sizes, allowing you to choose models with a sufficiently large bottom area for your group of fish. Matching stands and covers help ensure stability and safety, which is especially important in households with children or pets.

In addition to tanks, MB Store provides complete filtration systems, heaters, thermometers and aeration equipment. Thanks to this, you can assemble a coherent and efficient technical setup that will ensure constant water parameters and proper oxygenation. The store’s assortment includes substrates, decorations and plants suitable for Corydoras, enabling you to create a natural-looking environment that supports their instinctive behaviour.

Food and water treatment products available in MB Store also play a key role. High-quality sinking pellets, wafers and specialised nutrition for bottom feeders help you build a varied and balanced menu. Conditioners and preparation kits neutralise harmful substances in tap water and stabilise pH and hardness, making regular maintenance easier and safer for fish.

By using the offer of MB Store, you gain access not only to equipment but also to knowledge. Carefully described products, parameters and intended use make it simpler to match them to your specific setup. Whether you are just starting your aquarium journey or expanding an existing collection, the right choice of equipment significantly increases the chances of success and long-term satisfaction with keeping Corydoras catfish.

FAQ – Corydoras Catfish in the Aquarium

How many Corydoras should be kept together?
Corydoras are schooling fish and should never be kept singly. A minimum group of six of the same species is recommended, although 8–10 or more is even better. In larger groups they feel safer, display natural behaviour and are less shy. Always match the group size to the available bottom area of the aquarium so the fish have enough room.

What is the best substrate for Corydoras catfish?
The best substrate for Corydoras is soft, fine sand that allows them to dig safely. Their barbels are delicate and sharp gravel may damage them, leading to infections and feeding problems. If you use gravel, it must be very smooth and rounded. Regular cleaning of the substrate is also important to prevent food residues from rotting and harming the fish.

Do Corydoras clean the aquarium so I do not need maintenance?
Corydoras help by eating some leftover food from the bottom, but they do not replace regular maintenance. They do not consume fish waste or all detritus, so water changes and cleaning are still essential. Overfeeding will quickly pollute the tank, even with a large group of Corydoras. Think of them as helpers, not a complete solution for aquarium hygiene.

Can Corydoras be kept with shrimp and snails?
Corydoras are peaceful and generally safe with adult shrimp and snails. They do not actively hunt invertebrates, focusing mainly on food particles in the substrate. However, very small shrimp, especially newly born ones, may occasionally be eaten if they appear directly in front of a foraging fish. Providing dense plants and hiding places increases shrimp survival rates.

What temperature and pH do Corydoras prefer?
Most popular Corydoras species feel good at temperatures between 22–26°C and slightly acidic to neutral pH, usually 6.0–7.5. They can adapt to a certain range of parameters if changes are made slowly. The key is stability: avoid rapid swings in temperature or pH. Use a reliable heater, thermometer and regular testing to provide consistent, comfortable conditions for your fish.