Your fish are great, I use to have 2 red Devils also, a male and female, they were very hardy fish. They always tore up the tank too. With a fish that size it's a good idea to give them a thick gravel bed so the can build thier own home. If they have enough they will push it up to all 4 sides. It makes then feel safe. Have you tried lage rocks in the tank as ornaments, he wont be able to tear that up. Any lagre rock you find out in the yard, just wash it well and do a PH, alkalinity, etc. test after it's been in there to be sure it didn't effect your water. My tank is full of slate rock and other rocks. Big fish = Big ornaments/everything.

Also, you know that red devil are only mid aggressive fish, maybe yours has a real bad attitude.


Here's a picture of my albino Oscar (flex), had her sence she was 1/2" long (baby) She almost 4 years old now. I don't know who told you that Goldfish gave your Oscar hole in the head or that they are even bad. It was most likely that the goldfish where sick or something in the water did it. But goldfish are fine to feed to them if they are healthy goldfish. Just don't keep the goldfish in there too long (days) They produce high ammonia levals. My Flex had been feed them for years now, she has never been sick.