Why Do Koi Lose Scales
📝 Summary
Koi lose scales from external stress (transport bumps, crowded tanks, sharp decorations, fighting, fright) or disease (dropsy, hole-in-the-body disease, red-skin disease). Good water quality and avoiding bacteria greatly lower the risk.
1 Why Koi Lose Scales
Scale loss is common and can signal stress or illness; find the cause promptly. Here are prevention and treatment pointers.
Causes and Measures
Find the cause first. Disease-related loss comes from bacterial infections (dropsy, hole-in-the-body disease, red-skin disease). Poor handling, aging water, or new fish can trigger bacterial or viral outbreaks. Stress from sudden water changes causes fish to crash into the pond wall.
1. Transport: bumpy rides stress fish, causing collisions and scale loss. Quarantine new fish and let them settle.
2. Sharp decorations: remove hard or sharp ornaments that scrape fish; even play-chasing causes scrapes.
3. Mixing species: koi are gentle; avoid housing them with aggressive fish to prevent fighting and scale loss.
4. Overcrowding: too many fish collide and compete for food. Control density.
Parasites also cause loss — they attach to the surface and fish rub against walls. Observe swimming, eating, and lesions; act early. Keep a suitable environment and proper density.
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