Is a 55g tank enough living space for two clown loaches and an oscar fish?
It would be very marginal as far as fish happiness. Oscars can grow to a foot, and believe it or not, Clown loaches can come close to that! Not very nice to have one of the aquarium dimensions the same as the fish length! I did have some breed in a 55, but they weren’t full grown. I agree with retroglide – a 75 gallon would definitely be better. Probably the best overall would be a 125 gallon from Craigslist. Let us know.