Metal Corydoras – Breeding and rearing

© Daniel Nimmervoll

Wild catfish, Corydoras aeneus, start laying eggs in autumn. Offsprings, which swim in domestic aquaria, spawn regardless of the season. For a good breeding success not only a few important basic conditions have to be created, but also the age of the fish plays a decisive role. The older the animals are, the less young are to be expected. The best breeding success can be achieved with animals aged between ten and eighteen months.

Necessary conditions for breeding

To determine the sex of the armoured catfish is not so difficult at all.


  • full, robust body
  • rather slim build
]A 10 liter tank is sufficient as a breeding aquarium. In the community tank there is the danger that the eggs are eaten by other fish. The water must be soft and slightly acidic. The tank should be equipped with a fine sandy bottom. The planting can be quite sparse, a large-leaved plant is quite sufficient and filtration of some kind is absolutely necessary.

If the Metal Corydoras are sluggish and somewhat stubborn, the water level in the tank is reduced by 30 to 40 percent within a week. Afterwards the water taken out is replaced with fresh water. The water temperature should be lower than the temperature in the aquarium. This imitates the natural conditions of life. In the wild, the metal armoured catfish start to spawn in time for the rainy season to begin.

The courtship behavior

Corydoras are sociable and playful animals. During the mating behaviour the males follow the female, which is looking for a suitable place to spawn. Excitedly the animal swims around in the aquarium and from this behaviour you can clearly see that the fish will soon start spawning. A male will position himself in the typical T-formation directly in front of the female and both male and female will start to tremble.

The spawning behaviour

The female trapped the eggs between her ventral fins. This also explains the extended, fan-shaped fins. As soon as the female releases the eggs, the male releases his sperm to fertilize the eggs. The female then places the adherent eggs on a smooth surface that she has previously cleaned. The smooth surface can be a plant leaf or, more likely, one side of the pool. Whichever surface the female chooses, it is in the upper regions of the water and not on the sand or stones.

Breeding care and feeding

After egg deposition it is recommended to remove either the adult fish or the eggs from the tank. The eggs are removed with a ruler or razor and the eggs are placed very carefully in a sieve. The sieve is hung in the tank so that it is just below the water surface. The water in the sieve has to be renewed again and again with an air-operated sponge filter. After about 48 hours the young fish hatch.

Breeding of the young fish

After sucking off the mucus coating, the young fry is placed in an uninhabited tank and fed with freshly hatched brine shrimps. When the young fish have grown up, they are fed daphnia and crumbled flakes.

Accessories for breeding:

  • Breeding aquarium
  • Filter
  • Plastic sieve
  • Gravel or sand
  • Cave
  • one or two plants

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