Indeed, in some extreme cases, it can happen that the fish, which have themselves fertilized their young, find themselves eating them some time later. Most of the time, this is an accidental phenomenon, more than anything else. We explain everything in this article:
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Why do fish eat their young?
It is above all a story of natural selection! Even if it may seem cruel for a civilization like ours, fish eating their young is a not so rare phenomenon, especially when they are in a community tank!
Male freshwater fish, which guard and protect their offspring, sometimes tend to confuse the nest with a pantry.
Fertilization in freshwater fish is external. That is, the males release their sperm into the water where the females have deposited their eggs. The males are then responsible for protecting the nest from predators, as well as aerating the eggs by beating their tail.
During this period, the male cannot decently leave his dear little ones unattended. The only way he can feed himself is to draw from this young fish tank.
How to prevent fish from eating their babies?
The only viable solution is to separate the babies from the community tank until they reach an adult size and weight.
You can retrieve some eggs by removing a spawning medium from the aquarium (plant, rock or other decoration) to raise the fry in another tank.
Unfertilized eggs dissolve and often lead to the development of saprolegnia, a fungus that can contaminate the developing embryos. It is very important to remove the white eggs by sucking them up and adding a few drops of an anti-fungal liquid such as 5% methylene blue (harmless for fish).
After 4 to 5 days the first fry hatch. The larvae attach themselves to the leaves of the plants or the windows, avoid direct sunlight which can be fatal to them by putting newspaper on the outside walls for example.
The newborns have a closed mouth and have a nutrient pouch from which they draw their food until they are able to swim. At 6 days, the fins appear and the mouth has developed. After a week, they begin to swim freely and become fry that must be fed.
How to care for fry separated from their parents?
It is recommended to feed the fry several times a day in small quantities, at least 4 times a day. Different kinds of fry food are available in the shops, but you can also prepare them at home with hard-boiled egg yolks sieved through a fine sieve to obtain a powder.
Two or three weeks after the beginning of the feeding, you will distribute slightly larger food: artemia nauplia and small freeze-dried flakes are recommended because they are rich in proteins.
As they grow, you will have to adapt the size of the food based on the principle of a food the size of their eyes. When the young goldfish measure more than 2 cm, it will be possible to feed them as adults and to gather them with their parents.