My vote would be africans. you wont be able to keep more than 2 adult oscars in a 90 but if you stocked your tank with mbuna, you could have a whole colony in your 90 gallon... :thumbs: :thumbs: :thumbs:
plus oscars are very messy and require more filtration, more food and way more water changes than the average fish in our hobby...
I had taken the grating off a section of the pond for a water change and never put it back on...
also, recently added another large catfish, it had/has been charging at some off the bass..
I'm going to guess that she got spooked and jumped..