thanks for the advice! I was thinking that I would move the puffers when they got big/aggressive. They seem alright for now though, they hide in the plants a lot and don't pay much attention to the other fish. - they're growing quite fast though...
I have a couple of teeny snails that came in with a plant I bought... I left them in thinking the puffers would eat them. But I've seen one of them trying to eat the snail but it can't dislodge it from the glass...
My lfs sells a large variety of frozen foods, so I'm sure I'll find something there - i'm pretty sure they have cockles. Are you sure though? Don't cockles live in the sea and aren't collomesus puffers freshwater?? These are my first ever puffers though so I'm a bit of a newbie...