So my brown knife has recently been rubbing/ "flashing" against plants and other objects in the tank. He has no white spots and none of the other fish in the tank are doing this. I am monitoring him closely but does anybody know if brown knives or other fish for that matter just randomly do this sometimes without having an ich type infection? I treat the water with PRIME when i do WC's (approx 10% twice a week) so the slime coat shouldn't be an issue.