Before I went to work I took to of my baby o's and put them with 3 that are 2x as large because the tank is bigger and these two are finding new homes by tuesday. When I got off work one of my larger o's my tiger to be exact has 2 seperate chunks missing from his head and still had some skin attatched. I think he ran into something so I changed 50% of the water addes stress coat and stress zyme and added some freshwater salt. I am hoping it clears up really soon but it looks pretty deep. I am going to do 50% water changes daily untill it is completely healed.

i seems that u hv done the right thing by adding salt,stress zyme & stress coat.

if yr O is still acting normal u shouldnt worry to much as oscars heal very quickly when water conditions are good.

keep an eye on him and make sure the others dont start hassling him.

a month ago my one tiger oscar swam into the the driftwood and had a huge hole in his head right between the eyes within 5 days it healed nicely and i had no problems.

ensure you keep the water top notch so no infections can start and u should be ok.

hope this helps & keep us posted.

Seems to me that the injured oscar has either been fighting or has injured himself. When a new fish is added to a tank it can upset the balance of the fish in the tank and they then have to reassert themselves and the pecking order thus the possible fighting and aggression. As vbaby said you are doing the right things and hopefully the oscar will heal quickly

I'd say if the O is swimming fine, he'll be alright. Mine does that sometimes, swims into something very hard and scrapes a chunk out of himself. But he heals quickly and he's always been fine. Just watch the interactions between all the o's.