I have a long finned Oskar that is about 4 inches now in 40 gallon tank with just him in it. What does anyone recommend for the algae that is in the tank - he attacks any fish including my 8" pleco.....Any ideas would be helpful

I have a convict and a red devil in with my long finned oscar - he is about 6 inches....I use nothing and leave it to them - no live fish feeding....but there is a chemical that divides the algae from the water - helps alot actually. it's called Clarity