Question
I think my black carp is pregnant. It is so big that it looks like it could burst at any time. I am worried that it might be egg bound - I have never seen a pregnant fish before. Should I do something? It is in my garden pond with another carp, two goldfish and a tench.


Answer
Pregnant koi/carp will be slightly enlarged but not large enough to burst.  It is likely that the koi has either an internal bacterial infection or a kidney malfunction.  Egg binding may happen if you don't have a male to help her lay the eggs.  Egg binding isn't as common as dropsy where the fish gets fat, and the scales stick out.  Egg binding can lead to dropsy or something similar.  With kidney malfuction, the fish accumulates fluid because it can't pump it out, slower gets fatter, and eventually literally explodes.  Unfortunately, dropsy isn't easily treated.  Antibiotics may help a little but much more if you can get someone to inject some (usually requires a fish vet).  Aside from antibiotics, adding pond salt can help make things easier for the fish.  My fish health page has some more information at http://www.fishpondinfo.com/health.htm that may be of some minor use.  Good luck!

Robyn