Anyone who has kept tropical fish at home has probably noticed that their fish lose scales, especially when there is a large area of scale loss. In such cases, it's important to analyze the cause and determine if the loss is due to a disease.
There are many reasons why tropical fish lose scales. Improper handling, such as when handling or cleaning the fish, can cause scales to fall off due to the equipment hitting the fish. Other causes include the fish being startled and hitting the tank, damaging its scales, improper feeding methods causing other fish to fight over food, and being bitten by other fish (this is especially important to consider when keeping arowanas with other fish). However, the most common cause is disease, such as saprolegniasis, drop scale disease, scabies, and external parasites.
Most tropical fish cannot regenerate their scales after they fall off. Scale loss is a relatively serious problem, often caused by a severe disease in tropical fish. Fish diseases have a low cure rate, and even if cured, they can leave significant scars. After scale loss, first check the water quality. If the water quality is poor, disinfection is necessary. Use a UV lamp to eliminate harmful bacteria in the water, combined with nitrifying bacteria to promote a dominant population of beneficial bacteria. Administer oral antibiotics, such as compound sulfadiazine or enrofloxacin. The most common cause of scale loss is disease, such as water mold, droplet disease, scabies, or external parasites. A 1% saline solution bath can be helpful.
However, fish do have a certain regenerative ability; lost scales can regenerate, although this takes time, and the regenerated scales won't be perfectly aligned or of uniform size. We should focus on prevention before fish develop diseases, rather than treating them after problems occur.
