Only one oscar would work in a 75. None would work in a 55, it's too small for them. A 75 also isn't ideal, you should have bigger if possible.Welcome to Fishlore For two oscars, a 75 gallon tank is the absolute minimum. 55 US gallon tank is the absolute minimum tank size to house an adult oscar.
Crickets, blood worms, cichlid sticks, shrimp, prawns, white fish, super worms will all be fine for Oscars. You should move them to a larger tank before you feed them any of these things. Oscars grow fast. And 10 gallons is too small for even a grow out for them.I got two new baby oscars about 3 weeks ago and I want to know if I can start feeding them something else besides the pellets at this time. Any answers?