Question
hi robyn, we have a small garden pond to which we have some goldfish, and 3 baby frogs. 4 of our goldfish look pregnant (swelling on underside near tail fin?) i am not sure what to do. do i separate them from the other fish or leave them alone? we are also finding it difficult to keep the water clear. please help.  

Answer
When a goldfish becomes egg laden, she becomes slightly enlarged.  If she is huge or really fat, she is probably not full of eggs.  This section on my site is entitled, "Why is my fish fat?" and lists some possibilities:
http://www.fishpondinfo.com/health4.htm#fat

Dropsy is the most common reason for a goldfish to become large.  If the scales are sticking out, it's dropsy.  If the entire fish slowly gets huge, it may be a kidney malfuction.  Goldfish can also have localized cysts and tumors full of fluid, fat, or rarely, cancer.  Most of these problems are not really treatable unfortunately.  Treatment with pond salt and antibiotics sometimes creates some improvement.  The bacteria that cause dropsy and other internal bacterial infections are ubiquitous which means they're always in the pond.  For that reason, there's usually not a concern about transfer of the problem to other fish.  Since you have four that are enlarged, that is a concern that maybe there is a cause (other than the individual fish) for the fish to have become enlarged.  Have you checked the water quality for pH, hardness, ammonia, and nitrite?  Do you do any water changes?  What do you add to the pond?  How big is the pond?  Since the water is not clear, that may be a factor.  Is the water brown, yellow, green, or white?  If it's green, that would be algae which shouldn't cause the fish to swell.  My page on algae control is at http://www.fishpondinfo.com/plants/algae2.htm
I don't normally separate fish with dropsy, tumors, etc. from my other fish because it's a lot of work to quarantine them.  But, if you can do that, the fish may have a better chance of some sort of recovery.  It's certainly easire to treat them in a smaller aquarium or pond.  I list some treatments at http://www.fishpondinfo.com/fishcare/treat.htm

Good luck!
Robyn