However, in the majority of cases it is because something is irritating them. Whether you should act or not depends on the number affected, the frequency of rubbing and leaping, and the vigour involved. If one or two are having a lazy rub on the bottom drain there is no cause for concern, this is fairly normal. But if they are continually tearing about, rubbing vigorously against the sides or bottom or leaping out of the water, then further investigation must he carried out. Unfortunately, one of the most common responses to this type of behaviour is to suspect a parasite problem and an anti-parasite treatment is administered without further thought.
Many fish suffer or die every year through inaccurate diagnosis and inappropriate treatments.
Skin and fin damage Frayed and damaged fins, raised scales and skin damage, such as reddening or open wounds, are often attributed to the fish cutting or damaging themselves on sharp objects in the pond. Although this can happen it is not common, spawning being the exception. Believing this to be the cause, many aquarists leave the 'wound' to get better, but invariably it just gets worse. The commonest cause of this type of damage is bacterial infection. Such instances need immediate attention.