i agree with delboy your tank is definetly overstock. as for the fin problem a pic will definetly help in figuring out if its from aggression or parisites. personally i would rehome 3 of your o's or setup a bigger tank to house all five. for that i would suggest a tank in the 200 imp gallon range.

good luck with your o's

thanks for the help guys but he has died now as soon as i put him in a tank by him self he ended up dying after a few days all the other fish are fine now , ive just got a new tank biult witch is 10ft x 3ft x 2.5 ft so its a prety big tank i brought three more oscars now so i now have 7 oscars in the tank with plenty of space and hidy holes and there are 2 now that are looking for a spot to start spawning witch is a good thing and a bad thing considering they are looking to spawn in the midle of the tank so the other oscars will be going near them and they will get fustrated ill probly just put them in another tank until they spawn and raise there fry then ill probly put em back in
thanks againg for all ur help guys to bad he didnt pull through hope to see u in other threads on the forum

sorry to hear about your fish. Unfortunately, it's something we will go through at some stage. I thought my tank was big enough, would love to see some photos of your big tank

Sorry about your loss. When you keep livestock sometimes some will die unexpectedly.

Your new tank is massive. I would love a tank that big, i doubt my girlfriend would think the same though