i have two oscars in my 77 gallon. they are being moved to my 135g when the stand gets made... but they've done just fine. i have a fluval 404 on the tank... do weekly water changes and they have MANY tank mates!

my giraffe catfish is in there with them, 2 texas cichlids, 2 sun catfish, a pleco, a 3" venustas and another cichlid (can't remember the name but the same size as the venustas).

is the tank heavily stocked... yup. do i do a lot of water changes... yup. are they all doing great with absolutely no disease at all... yup.

so can it be done... yup. can you do it and be lazy about water changes... nope.

i overstock most of my tanks though... i also over filter them to make sure the water is top quality as it's what they live in.

if i lived in a toilet... i would SO want someone to flush at LEAST once a week!

oh and my oscars love each other. no problems at all between them. felix and brindi are their names... my little puppy dogs! (and very pouty when i do their water changes... they very very VERY much dislike water changes LOL)