Please help me you guys!

[KyleMoore]

My darling Oscars who are about 3" and 5" are getting scratches and digs on them, they usually heal up but then they do it again and sometimes losing scales etc and it really upsets me to see this. The only things that could have happened to change this is the recently added a clown knife but i don't think it is anything to do with him because he hides all day and only comes out at night when i leave some food out. The only other fish i have in there is a 4" jack Dempsey. I went away this last weekend and according to my mum the electric when out and the filter didn't fire back up. So the filter was of for about 50 hours causing a slight build up of waste on the substrate but i cleaned it this evening like just now. I feed them on hikari cichlid staple and frozen cubes and recently river shrimp, So i do given them a varied diet. I cant seem to see any scratches on the other fish?

Please Please Please Help Me Guys,
Im so worried im going to wake up and see a horrible gash or something.

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[rwellbaum]

tank size?
do you have any sharp decorations in the tank?

 

[KyleMoore]

I just have bog wood only, I did have a slighty sharp decoration which i have removed.

Its 4x2x2. Im getting a 700l tank this weekend.

 

[EBJDguy]

I had this problem with my oscars at one point. I found out they were running into the filter intakes during the night. There were no sharp decorations, only fake plants. A way to fix it is by switching to canister filtration or upgrading to a much larger tank. If I had to guess, your oscars are in a 75 gallon or less tank. If they are in a 55, consider an upgrade to a 125 or better.