I used a foam roller for the first coat or 2 and started having some issues. I think I just got a crappy roller because it wasn't turning easily. It would get caught up and then just drag. Come layer 2 I was pulling up dried paint as I went and switched to a foam brush. I would poor a bit of paint on and gently brush it out.
I had my tank on it's side and set up a flash light inside pointing at the back. It really helped me spot the areas that needed another coat of paint too.
1 fish, 2 fish, red fish, blue fish