Swollen fish

Question
Hi

I have a goldfish which has swollen up like a balloon, his scales are standing off his bod in places I therefore beleive it could have dropsy - what should i do with it ? It's in a tank with three other fish ?

Answer
I certainly sounds like Dropsy.  It is generally caused by a bacterial infection.  If you have caught it soon enough you can try treating it with medication specifically for Dropsy.  Unfortunately, it is not always treatable.  If the infection has affected you fish's kidneys, then it will likely die.  If you can, separate the fish from the others to treat it and if you can't, then be sure to remove it IMMEDIATELY if it dies.  If the other fish pick at the dead fish they can ingest the bacteria.  It does not generally spread to other fish and I suggest you also have your water tested to find the cause of the illness. Also you should do 25% water changes every 2 weeks (or 10% a week) to help keep your tank clean.