I would discontinue the MG/3X sulfa. While it didn't work, it may have provided hints as to what this may be and how to attack it. The same way dropsy is an external manifestation of and internal issue. I think this may be some combination of both. I was doing some reading about this and while there isn't a great deal of information reguarding specific issues as they relate to gars I think this should be attacked on two fronts. I'm looking at a combination treatment using Kanamycin and Metronidazole. Kanamycin treats several fungal and bacterial diseases which includes Dropsy, Popeye, tail rot, septicemia and flexibacter because it is very well absorbed it is very affective in treating both internal and external bacterial and fungal infections. Metronidazole is effective and safe treatment for several protozoan and anaerobic bacterial diseases. They are safly used together and provide very effective broad spectrum coverage for a combination of bacterial, fungal and protozoan based diseases.