Hi.... i have an 11" arow in a 120g (48x20x28) and every time i turn the lights on in the morning he has missing scales and scrapes on him.... there is nothing that will disturb him during the night....he is never jumpy in the day....he always comes to say hi to everyone who looks at the tank....i dont know whats up...i have wittnessed it before he jumps gets stuck on the glass support and flaps about until he plops back into the water...i dont want him to get stuck and die.... HELP! please 
