Well i went out and bought a 20 gal tank and i treated all of my fish for the last 3 days in the old tank and the one that was sick looks %100 now but i had the new tank all set up for them and i put them into it today....But my biggest fish is a male and he seems to really really b aggressive with the other fish except 1 that i think he is mated off with...he is really hurtin them....should i move him and the female he seems to b mated with into the old tank ?