Pygmy corydoras

Aquarium fish: Pygmy corydoras (Corydoras pygmaeus)
Size: 3 cm
Origin: South America
Water temperature: 22-26 ° C
Aquarium volume: 30 l

Pygmy corydoras (Corydoras pygmaeus ) – a miniature freshwater fish from the Kirysk family. Often mistakenly called a dwarf cuirass .


It occurs in the Madeira river basin in Brazil. It lives in small tributaries, streams, watercourses and flooded forest areas. It mostly hides between vegetation and tree roots.

Characteristics and disposition

It grows up to 3 cm in length, but usually less – males about 2 cm, females 2.5 cm. Club-shaped, silvery body. A black uninterrupted line runs along the sideline from the snout to the root of the tail. A second thin black streak runs down the lower body from the pelvic fins to the tail. The upper body has a dark gray or brown shade.

The fry in the first month have a vertical band that fades and a horizontal band appears in its place. The sex , as in the case of other cuirasses, is best distinguished by looking at the fish from above. Females are often larger, rounder and wider than males, especially when spawning. A very gentle and calm species. In nature, it lives in large groups.

A minimum of 6 individuals should be kept in an aquarium , preferably 10 or more. In a large group, they look prettier, are bolder and exhibit more interesting behavior. Interestingly, compared to most cuirasses, they swim more often in the water , but at the same time much less frequently than C. hastatus . Then they stick to the shoal nicely – the fish “take off” one after the other.

Like other cuiras, they do not have scales, and their body is covered with two rows of bone plates. The first rays of the pectoral and dorsal fins are hard and sharp – be careful when catching them as they can easily become entangled in the net or prick painfully. They are adapted to survive in oxygen-poor waters. They have an additional respiratory organ – a modified intestine, which enables them to take in atmospheric air from the water surface. In an aquarium, they often swim rapidly to the surface to draw air, which is perfectly normal and natural behavior.

Nutrition and feeding

Omnivores, they will eat any food that falls to the bottom of their mouths. On a daily basis, they can be fed good-quality fine dry foods in flakes or granules. The diet should be regularly supplemented with live and frozen foods, e.g. brine shrimp larvae, daphnia, hydration, tubifex, copepods. A varied diet keeps the fish in optimal condition.

Under no circumstances should they eat solely on scraps left behind by the rest of the cast.


An aquarium for a small group of pygmy cuiras should be at least 30 liters (preferably larger). They feel best in a not too brightly lit and locally densely planted reservoir with a dark, sandy ground. Floating vegetation is also recommended. For decoration, you can use dry branches, roots or leaves, which will give the aquarium a more natural character.

Kiryski pygmies prefer moderately acidic and soft water, but they also adapt easily to other conditions. They are extremely sensitive to all contaminants , chemicals and drugs, as well as sudden jumps in parameters. The water should be of excellent quality , regularly changed, and the substrate should be desludged frequently. Symptoms of stress usually begin with rapid breathing, followed by lethargy (frequent and long sitting on plant leaves or the ground), and sometimes they turn sideways. Any sudden change in water chemistry or temperature will often cause a shock, causing the fish to ‘swoon’ and roll over or to start swimming strangely.

Introduced into an unstable aquarium, they die within a few weeks. In a social aquarium they can be combined with similarly sized, gentle species. The perfect company will be razors, trout, microorganisms, blue-eyed rainbows and small tetras from the same region.


It is most willing to spawn among the miniature cuirasses . In a well-kept and arranged aquarium, breeding can take place quite unexpectedly after a major water change.

A more controlled approach is required to obtain a large number of fry. You will need a separate spawning tank (min. 20 l) with mature sponge filtration and large clumps of plants (Mikrozorium, Java moss) or alternatively with an aquarium mop. The fry appear less susceptible to disease when buried in a thin layer of sand. Fish for spawning are stimulated by a large change of soft and acidic water, a few degrees cooler than that of the main aquarium (water is changed gradually).

The water should be soft and acidic. Filtering it through peat or using an RO filter will help. The use of additional air stones will increase the movement of the water and the amount of dissolved oxygen in it. This simulates the rainy season when the fish rub under natural conditions. Experienced growers also talk about the beneficial effects of the storm and the associated sharp change in barometric pressure.

Specimens at the age of 10-12 months start spawning. Before spawning is planned, the amount and frequency of feeding live and frozen foods should be increased. During the spawning season, pygmies’ cuiras are more vigorous. The males chase the female around the aquarium and the winner of this competition wipes the female as a reward. The female takes the dandelion from the male (in the T-position typical for cuiras) and releases the already fertilized eggs (2-4 pcs.) Into a pocket made of pelvic fins.

Then it flows off and puts them in a selected place – it can be, for example, an aquarium glass, substrate or plant leaves. Parents who are well fed will not pay attention to the eggs, but it is better to separate them to maximize the amount of fry obtained. It is a good idea to add a few drops of methylene blue to the spawn tank to partially prevent mold from forming. Alder cones also exhibit similar properties. Some growers even use certain species of shrimp that only eat moldy eggs and leave the healthy ones, such as the popular red cherry shrimp.

Hatching time depends on the temperature, it lasts from 3 to 4 days. After another 4-5 days, the fry begin to swim freely. We feed the fry with powdered or liquid micro-foods. In the first days, it can take on micro nematodes, and after a few more, freshly hatched Artemia larvae.


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