Update

So, I have now seperated my fish into 2 tanks. The two of mine that are just lying on the bottom most of the time are together, and the (so far) healthy one is on his own in the kitchen.

I have fasted mine for 24hrs, and now fed them some shelled peas in case it's a touch of swimbladder (I dont think it is because when they do swim they seem ok). They swam artound for about an hour eating all the bits off the bottom of the tank, then just went and lay down again.

I was thinking of going and getting some meds for swimbladder, as well as gill flukes which apparently can also case these symptoms.

Is it ok to treat for both together?

Hmmmm... it's not generally recommended to mix meds. If they can swim I doubt it is the swimbladder so I'd go with the gill flukes or a general 'cure all' combined with plenty of oxygen, clean water and lights out.

Same as indi here

Thanks, I'll get some meds tomorrow