Problem with Fantail Fish & Shubunkins

Question
Hi there, hope you can help me. I have a medium size tank approx 3ft in length, 2ft high and 1ft deep. I have a number of freshwater fish inc Goldfish. Comets, Coy Carp, Shubunkins and fantails.  The problem is that a few of the shubunkins are ganging up on one of my fantails and nibbling at their tail and rear end. I am not sure if the fantail is male or female but they only seem to pick on this one. I have taken it out of the main tank and placed it in 'quarantine' so to speak. The fish seems in good health, slightly swollen but that's it. Could it be pregnant? Do you think the other fish are after her eggs? I would appreciate any help regarding this matter.
Thanks,

Paul McCrickard

Answer
Hi Paul
It's possible they're trying to mate or spawn with it.  Does it look swollen in the belly area?  It's possible it's a she full of eggs.  But, there is a "condition" that all fish can get, and it can resemble a female full of eggs.  It's called dropsy, and basically it gives the fish a swollen appearance, eventually their scales stick out like a pinecone.  It has a number of possible causes from an internal bacterial infection, internal parasites, poor water quality, etc.  It's really not treatable.  

At this point, I would go ahead and keep the one separated.  If it is a female, and assuming the others are males, they can stress her out enough and end up killing her.  Keep an eye on her for other symptoms as well.

Christy