Can I put an oscar with two plecos?

Adult plecos will fight with each other. So I would re-home one now. For a Oscar and a common pleco to stay in the same tank, you will need a 75 gallon with a ton of filtration. Like a Eheim 2262 or a Fluval FX5. A larger 90 or 110 gallon would be better ,or a 5' 120 gallon would be best.

A 55 gallon is not suitable for any of these fish.

55 gallons is too small for 1 pleco or 1 oscar. For all 3 you would need more like 125 150 gallons.

Not in a 55gal tank. Any of those fish alone can outgrow a 55gal.

Oscars and plecos do make good tankmates, but it needs more space for 2 or 3 large messy fish.

You are more likely to see aggression between the 2 plecos as they get territorial and fight over space as they get bigger.

ian

too small. if you have common plecos you need at least 300 gallons to keep more than one as they are pretty aggressive to their own kind.