Do you know the fish Corydoras? If you are an aquarium enthusiast, you have probably heard of these small fish known for their essential role in maintaining cleanliness at the bottom of the aquarium. This article aims to become the most comprehensive and up-to-date guide to Corydoras, covering their origin, characteristics, recommended species, habits, behavior, compatibility, care, feeding, reproduction, longevity, and much more, integrating all the latest and most relevant knowledge to thoroughly care for these fascinating allies of aquatic maintenance.
Origin, classification and geographical distribution
The Corydoras are part of the family Callichthyidae, which is subdivided into two subfamilies: callichthyinae y coridoradinae. You can find such well-known genres as Aspidoras, Brochis, Callichthys, Corydoras, Dianema y Hoplostern. Of the genre Corydoras there more than 150 classified species (some sources speak of higher figures) and at least 30 still unclassified. This extraordinary diversity gives them a unparalleled versatility for integration into aquariums of all sizes and styles.
In nature, Corydoras They are native to South America, distributed throughout the Amazon basin and numerous tributaries from La Plata in Argentina to the extreme north of Venezuela, including Brazil, Colombia, Peru, Bolivia, Paraguay and Uruguay. They are emblematic inhabitants of rivers, lagoons and streams of clean water and slow to moderate currents, generally on sandy or muddy bottoms where they search for food.
Its great capacity for adaptation allows them to live in waters with temperatures that can range between 16 °C and 28 °C depending on the species, which makes them suitable for both tropical and mildly temperate aquariums. For example, the well-known Corydora aeneus It is distributed throughout almost all of South America, showing amazing plasticity in the face of environmental changes.
Corydoras: the real bottom-cleaning fish
There is a widespread myth that fish clean bottom Corydoras are "garbage collectors" who remove all the dirt from the aquarium on their own. However, this concept is not entirely accurate. While Corydoras stir up the substrate with their barbels in search of food scraps, They do not feed on excrement or decomposing waste; in fact, consuming this waste would be harmful to your health and that of the aquarium.
Its main role in cleaning the aquarium is to stir the substrate gently, helping organic particles to be captured by the mechanical filter and promoting bottom aeration, which prevents the formation of toxic buildup. However, They do not replace manual cleaning or regular water changes., which remain essential for maintaining a healthy aquarium.
This "maintenance" work is especially valuable in planted aquariums, since their constant movement prevents microscopic algae from settling firmly on the plants and decorations, thus indirectly helping to keep their proliferation under control.
Adaptation, morphology and natural defense
Name Corydoras comes from greek kory ('helmet') and dora ('skin'), directly referring to its characteristic bone plate armor along their flanks, instead of the typical scales found on other fish. These plates provide exceptional protection against predators and external aggression.
Present morphology adapted to the bottom: flattened body and head, straight belly, mouth facing downwards and equipped with two or three pairs of sensory barbels with which they delicately explore the substrate to detect food. Their size varies greatly depending on the species, from tiny specimens such as the Corydoras pygmaeus (2-3 cm) up to species higher than 10 cm and Corydoras barbatusIn the aquarium, they can live of 8 12 years and in exceptional cases, some reports have documented superior longevities.
The coloration of Corydoras responds to a camouflage pattern and adaptation to the environment. Specimens that inhabit sandy bottoms often display irregular spots or patterns that blend in with the background, while in muddy environments, brown or dark tones predominate. evolutionary chromatic versatility allows them to evade predators and adapt to different habitat conditions.
Ideal aquarium parameters and conditions
To ensure the well-being of your Corydoras, it is essential to replicate the conditions of their natural habitat as closely as possible:
- Temperature: ideal range of 22 °C to 26 °C, although some species can withstand lower or higher temperatures depending on their origin.
- pH: across 6.0 and 7.5, with a tendency towards slight acid/neutral.
- Hardness: soft to moderately hard, preferably GH between 4 and 12.
- Substratum: the most appropriate thing is fine sand or rounded gravel that allows digging without damaging its barbs. Sharp gravel should be avoided.
- Decoration: Abundant vegetation (natural plants), roots, trunks, hiding places, and dried leaves. The inclusion of tannins (leaves, alder cones, wood) helps recreate Amazonian environments and promotes the activity of Corydoras.
- Filtration: It must be efficient but not cause excessive currents. It is important to use mechanical filters to avoid turbidity caused by the constant churning of the bottom.
- Capacity and group: minimum 50 liters. Corydoras are gregarious, so it is advisable to keep groups of at least 5-6 specimens to observe all their natural behavior and avoid stress.
Behavior, habits and compatibility
The Corydoras are eminently peaceful and gregarious fish., displaying a social nature that manifests itself in swimming in groups and foraging together. This behavior reduces their stress levels and encourages interaction, making them appear more active, confident, and healthy.
In community aquariums they are the perfect choice when displaying excellent compatibility with most de peces fresh water of similar size and temperament. However, it's best to avoid keeping them with overly aggressive, territorial, or large species that could intimidate them or see them as prey. Fish such as large cichlids, medium-sized and larger plecos, or territorial botias are not the best companions, while tetras, small cyprinids, characins, and other Amazonian fish are ideal.
Su preferred habitat is the bottom, although they can sometimes be seen rising to the surface to take a breath. They have a supplementary respiratory system that allows them to swallow air through their mouths in low-oxygen situations, absorb oxygen through the intestine and expel the waste through the anus, a characteristic that increases its resistance to suboptimal conditions.
If you have multiple Corydoras, you should know that constant stirring of the bottom can cause mild cloudiness. Using a quality mechanical filter can solve this problem. This habit also helps keep the bottom aerated and prevents blockages in the biological filter.
Feeding Corydoras: balanced and varied diet
The Corydoras are omnivorous, which allows them to feed on both animal and plant sources. Although they are known as "cleaner fish," The food waste they find at the bottom is not enough.; therefore, it is advisable to supplement your diet daily with specific foods:
- Sinking tablets and pills formulated for bottom-dwelling fish.
- Live or frozen foods: mosquito larvae, brine shrimp, daphnia, tubifex.
- Crushed flake food and small granules.
- Occasional additions of blanched vegetables such as zucchini, cucumber, or peeled peas.
Remember to feed after the surface fish have eaten, so the food reaches the bottom and is not consumed first by other fish. It is important that the feeding is varied and balanced to avoid nutritional deficiencies, maintain intense colors and promote vitality.
Overfeeding should be avoided to avoid deteriorating water quality (high nitrite, ammonia, etc.). Offer the right amount they can consume in a few minutes and remove the excess. You can schedule "fasting" days to encourage their natural foraging instinct. Well-fed Corydoras actively contribute to the ecological balance of the aquarium ecosystem.
Sexual differences and reproduction
El sexual dimorphism In Corydoras it is not particularly pronounced, but there are some subtle differences:
- Females are usually larger. and have a more rounded abdomen, especially during the reproductive season.
- Males are more slender, with the dorsal fin somewhat more pointed.
- Some species show slightly more intense colors in males.
La reproduction of Corydoras It is relatively simple in popular species (Corydoras aeneus, paleatus, sterbai, metae), but it requires certain conditions:
- Keep groups of several males and females in the breeding aquarium (minimum 3 males x 2 females).
- Perform regular water changes with a slight drop in temperature to simulate the natural rainy season.
- Provide plenty of fine vegetation, leaves or smooth surfaces (glass, broad leaves, filters) where the females will lay their eggs.
The courtship process is fascinating: they usually group together and swim frantically, rubbing against each other until they adopt the cross or T positionThe female holds 2 to 4 eggs between her pectoral fins, which the male fertilizes. The female then deposits the eggs on leaves, glass, or decorations. Incubation lasts 3 to 5 days depending on the temperature. Once hatched, the fry are fed brine shrimp nauplii for the first few days, followed by crushed feed.
In some cases, reproduction occurs spontaneously if the environment and water quality are optimal. However, there are Corydoras species that remain difficult to breed in captivity, making them particularly sought-after among experts.
Most popular species and varieties
- Corydoras aeneus: Known as "bronze", it is one of the most resistant and adaptable.
- Corydoras paleatus: with a mottled pattern (grey, brown and silver), easy to care for and very active.
- Corydoras sterbai: It stands out for its elegant pattern of white dots on a dark background.
- Corydoras pygmaeus: tiny, ideal for nano aquariums.
- Corydoras julii: known as "leopard", with dark spots on a greyish background.
- Corydoras albina: a variant of the bronze, highly appreciated in aquarism.
Health, longevity and disease prevention
Corydoras enjoy great resistance to diseases thanks to their respiratory system and the protection of their bony plates. However, they can be susceptible to bacterial infections, fungi, and diseases such as dropsy if the water conditions are not adequate.
Main causes of disease:
- Poor transport conditions: Transporting large or small quantities can damage the fins. It's recommended to acclimatize them in small groups using clean, medicated water after purchase.
- Intense environmental pollution: Excessive nitrites, ammonia, and unremoved organic matter. The solution lies in keeping the aquarium clean, performing regular water changes, and avoiding overfeeding.
- Sharp substrates: Sharp gravel can cause wounds in the barbels, facilitating the entry of infections.
Observe the behavior and appearance of your Corydoras daily: An active, brightly colored fish with a regular appetite is a healthy fish. Healthy Corydoras are active, sociable, and display their natural group behavior.
In good aquarium conditions, They usually live between 7 and 10 years, although there are specimens that have exceeded that age and some records place their longevity at more than two decades in exceptional situations.
- How many Corydoras should I have? The optimal is at least five or six copies so that they can express their natural behavior and avoid stress.
- What type of substrate is best? Fine sand or rounded gravelSharp or pointed substrates can injure the barbels, which are essential for feeding.
- Are they compatible with plants? Not only are they compatible, they prefer planted aquariums, which simulate their habitat and provide natural refuges.
- Should I put a bottom filter? It is best to use external or sponge filtration to avoid injury and facilitate access to the substrate.
- How to detect if they are healthy? Observe activity, appetite, coloration, and grouping. A solitary Corydora is usually stressed or sick.
- Do Corydoras clean the aquarium by themselves? They help keep the bottom free of debris but do not replace manual cleaning or water changes.
Corydoras have established themselves as one of the most prized fish in the aquarium world thanks to their combination of ecological utility and aesthetic beauty. They are the ideal choice for those who want to maintain a balanced aquarium. healthy and active, as they offer a friendly, sociable, and dynamic presence at the bottom of the tank. With basic care and proper attention, your Corydoras will contribute decisively to the overall well-being of your aquarium and allow you to enjoy one of the most fascinating natural spectacles available underwater in your home.
