I am new to fishkeeping and am not sure what to do for the best. I
noticed this morning that my less than a year old comet, Dale, is
swollen mainly on the left side above the pelvic fin but perhaps a bit
on the right side also though not as much. He is sitting at the bottom
of the tank but will come up and swim around if I lift the lid then
when he realises nothing much is going to happen he goes back down
again. He is still eating and the water quality is within ok limits.
I have only had him and his tank mate, another comet, for 11 days so
cannot believe something has gone wrong already! Dale has always been
the slightly smaller of the two and the quieter and doesn't eat as much
but seemed perfectly healthy until this morning. I don't see any
raised scales or gasping or areas of soreness so what do you think it
could be and if it is possibly the start of a bacterial infection
should I start treatment straight away just in case. If so what to do
and should I isolate him or leave in tank to treat.