You said your pair was accidental. But, why would you purchase two of the same species, you do know by doing that you run a chance of having a pair?
When dealing with cichlids in a large community I never buy the same two types, for that reason. Personally, I would try to find the Red Oscar a nice home, IMHO more than likely it is the male Bahia beating down your Red Oscar. Clown Knives are usually only aggressive with their own kind.
I can't help but wonder if the op posted this thread just to get attention and start an argument...
If that isn't the case, the conclusion I've come to is - some people really are that dumb.
looks like a nice setup, i use the pool as well, how's it working for you? I like the pvc idea, never thought about that. I had a bunch of lily pads in my pool but the plecos dug all the dirt out of the pots so i scrapped that idea.
Thanks I like it alot, I got my pvc from scrap from a water main project one is 16" the other big one is 18". I would also suggest you have a patch kit on hand just in case.