Background

This bacterial or viral infection is fairly common, and affects all types of freshwater fish. Dropsy will occur when fish are in poor water conditions, or stressed for some reasons including;

• rough handling
• fighting
• overcrowding
• poor water quality
• incorrect water quality
• fluctuating temperatures.

However, fish in a healthy environment may occasionally be affected due to unknown source of bacterial / viral infection.

Dropsy is notoriously hard to treat; the mortality rate for fish with dropsy is high. If fish recover, maintain their tank temperature in the high 70's consistently afterwards as dropping temperatures may trigger dropsy again. 

Diagnose

Symptoms can include; 

• Markedly swollen body
• scales sticking up (giving a 'pine-cone' appearance) 
• reddening at the vent or base of gills
• ulcers on body
• long pale faeces
• fish stops eating
• paler gills
• markedly protruding eyes.

Treatment

It is best to remove the affected fish to a hospital tank and maintain perfect water quality. A broad-spectrum antibiotic medication can be used, and a low level salt solution may help as well. The temperature of the tank should remain a consistant 78 -80 deg. F. Medicated food will be necessary to help kill the bacteria from the inside. Other food should be highly nutritious and good quality.