Symptom(s)
Fish rub against solid objects and "flash" when they turn to rub their sides giving a flash of silver colour as their undercarriage is exposed. They may also leap out the water.
This indicates some form of irritation of either the skin or gills.
possible Cause(s)
1) This could be caused by raised levels of ammonia, nitrite or high/low pH. Widely fluctuating diurnal shifts in pH can also cause irritation. Check all water parameters.
2) Irritation can also be caused by ectoparasites such as flukes, Trichodina, white-spot etc on the skin or gills. Examine the gills.