It is caused by feeding your fish concentrated low quality dry foods.
How to cure:
Fish’s foods should contain substances necessary for normal growth, development, and functioning of all organs and systems.
Sera fishtamin Sera activant
Fish should be given a balanced diet. Add vitamins to the feed following instructions. Provide fish with live foods: Tubifex, bloodworm, Corehra, Daphnia, Cyclop, Amphipoda, and raw liver. Once a week, at the end of the fasting day give vegetable foods: Wollfia, water fern, scaled salad, and dandelion.