So I have an established tank with 2 Oscars, 1 Arowana, and a Red Bellied Pacu. The Pacu and possibly 1 of the Oscars is going to find a new home. My question is I am looking at adding a few new fish to the tank, including a Pleco and a Morey Eel. No one I have talked to knows how the Eel will interact with the Oscar and mainly the Arowana. The Oscar is ok sized, the Arowana is right over a foot long. The Eel is a young one and the reason I am considering this is because the Eel is a bottom feeder and the Arowana a top water fish. I have a Chiclid sand substrate with drift wood and rocks..4 Biowheel filters, 2 media holders, and a Canister filter rated for much more than the the tank it is in, and 2 Power heads. Ive never had an issue with water quality, and tend to keep the water brackish with a upper level pH. As with Oscars the tank is NOT planted and just has the drift wood and rocks. The tank is a 100 gallon and will be upgrading to a 300 gallon in January or Feb. Anyone have any advice? I havent actually gotten the Eel yet because this is a pretty expensive uh oh. I was also looking at putting a needle nose gar into the tank, and in the future possibly a stingray. Thanks