I think the main theory is that the same thing that causes Malawi Bloat in african cichlids causes this condition in bettas. National Fish Pharmacy theorized that parasites in the fish's GI tract caused damage that left the fish vulnerable to mycobacteria. Whether the bacteria are the cause or the result of damage caused by parasites is still up for debate--there really have not been any studies of this illness, so we can't draw any definite conclusions.
Whether the fish depicted can recover from their advanced stage of the disease is unknown, but there is a possibility that with an internal parasite treatment and antibiotics for addressing mycobacteria may help. There is no guarantee, though, since the swelling is likely caused by kidney malfunction and your fish needs functioning kidneys to process medicines.
Last edited by Adastra; 10-26-2010 at 02:09 PM.