peacock bass health

I have 4 peacock bass in my 5x2x2 tank..... Its been 1year, these guys never shown any abnormal behaviour or feeding delays...... Suddenly two of the basses, losts its appetite.... i was waiting for 15days till now.... trying with metrogyl 400mg (3days course).... this is my second day...

Lately I have noticed my peacock bass having a few scrape looking injuries on his head. My water parameters are almost perfect. What I think it is is just him accidentally hitting the bonsai tree I have in there. I just wanted to get a few different opinions on what it could be. Is there...