Mollies and a tiger barb

Question
Hi Tom
Well on Tuesday i bought 4 more Mollies to my 20 gallon tank 1male and 3 females (5 X-ray tetras 1pleco and a tiger barb).Any way when we bought the Mollies one of them was kind of fat but not much then the next day she was breathing heavily and looked MUCH fatter and she stayed close to the surface of the water I think she might be pregnant so we bought a breader cage and i put her in there this morning.Oh ya and the tiger barb is getting fat to around its anal fin I'm not sure if its pregnant because we have never had a tiger barb.

Answer
Hi Le Miserable,

This sounds to me like Dropsy. IF the fish are pine-coning then it's definitely Dropsy. If not get back to me ASAP!!

The disease is characterised by swelling of the lower abdomen. Swollen areas may show signs of pine-coning. However, this disease is often confused with pregnancy. Check your Molly's belly, if you can see small black dots then you're about to receive a brood of tiny mollies. Your barb is part of the Cyprinid family. Unfortunately Cyprinids are particularly susceptible to Dropsy. Livebearers on the other hand are very very prone to pregnancy! and obesity.

The disease must be caught early for any treatment to take effect. Adding salt (1tsp/ gallon) may be beneficial. Also, you could try over the counter remedies although the effectiveness of these tends to vary.

Dropsy is not contagious however remember that it is caused by different bacteria. Therefore, the particular bacteria spore may well be contagious so treat as quickly as possible. It is preferable for treatment to take place in a hospital tank if available.

Good luck!

Tom