Abdomen swollen
Lower body of fish is bloated and swollen to a considerable degree.
Virus infection with secondary infection by Bacteria Aeromonas punctuate. Seldom if ever seen in Aquaculture or wild catches, as infected fish will typically die before they can be observed.
Very difficult to treat successfully, infected fish should be immediately isolated, as disease is infectious. In Aquaria most affected species are Dwarf Gouramis, Bettas, & Black Mollies. Koi and other pond fish are often affected. Carp edema virus can cause high losses in ornamental species of carp as well as edible varieties such as Cyprinus carpio.
To prevent spread of disease best method is to take any infected fish and place them in a quarantine tank. Water in main tank and quarantine unit, should have ultra violet filtration to contain spread of bacteria, and all water parameters should be checked carefully and regular water changes should be done at least rice weekly for about 1/3rd of the tanks capacity. Always ensure new water is similar to old.