Clown sick

[HarleyC]

I've had to take him out DT. he was at bottom nearly sea and the others were starting to pull him around.
He has lost most his colour and on last legs (okay fins).
He is in bucket, but don't look good. Should I put pump in bucket with heater and get some treatment - if so what?
or, just let him go peacefully.
Still 1/2" long white stuff attached to one of the other clowns, but he looks healthy.
Any advice appreciated?
Tks