See where you went wrong is looking for the minimum size. I don't think an Oscar at adult size should be in less then a 120 standard 4x2x2 as the only fish. 75 is a good grow out tank until you start getting what you have going on. The Oscar needs to be in a bigger tank asap. You have people replying here that have more fish keeping actual experience in their little finger then you have and you are getting snippy with them? It's unfortunate you like so many others didn't look too deeply in to the research because if you had you'd have seen so many threads debating this exact thing and in the end its always the same as we have here. Consensus says needs a larger tank. Just because the first couple of posts says 55 or 75 or whatever doesn't mean its right. Look at who is posting, figure out how the forum works and you will see who the people are that give good advise. Imo no one is attacking you either don't be so defensive just accept the fact the research you did was probably rushed and the issue needs to be fixed. That may mean rehoming your fish and replacing with more appropriate fish for the space you currently have.I did all the research I could about these fish. Don't act like I don't know what I'm doing off of a single post. Every site including this one said 75 gallon minimum. After owning an Oscar I'd agree they need bigger and I'm working on it. The devil doesn't get as big as an oscar and I think a 180 is overkill for a single 8"-14" fish. And I said the 55 was a grow out its going in the 75 after I get my 125 going for the Oscar. The sunfish are going to get their own 75 after a few more paychecks. And psycho maybe to strong but the fish has gone bats@#$ compared to how he's been for the past 5 years in adequate conditions.