In layman’s terms, the fish has a bacterial infection and needs an antibiotic. How this happens is hard to say, but ammonia burn and heater burn can result in hemorrhaging that may or may not be indicative of a bacterial infection. If the fins have slowly been withering away leaving thread-like pieces and the water has been clean, the edge of the fins are etched in a white different from the fish’ native color, or the fins or body cavity shows red streaking, it’s usually bacterial. If you are near a store, Maracyn Plus is the best choice. If you do online, TMP/SMX AKA TMP Sulfa AKA Bactrim/Septra is best. Oxytetracycline, doxycycline, and minocycline (Maracyn) are also suitable. I am not sure that this is dropsy, however, it is at a pretty advanced stage and some of the symptoms are not met. Once that redness affects the body cavity to that degree, it’s very serious. It also appears that the fins show some red streaking, and the gills are inflamed…you need to start treatment ASAP. How fast did this happen? If it happened quickly, there is even more reason you need to begin treatment like right NOW without delay. Will fishy still accept food?
Also, as noted there is possible ammonia burn or heater burn…water needs to be as clean as possible with 0 ammonia. Bump your temp slowly as well if you aren’t around the mid-80s already.
Originally Posted by shellieca
I've had fish show dropsy even though they didn't seem to show any other symptoms before it set in. Unfortunately my experience with dropsy has not been good, none of the treatments I've ever used have cured it. I'm sorry, I wish had some advice that would work.
For dropsy, kanamycin + doxycycline (optional but seems to help) + vitamin B6 via trace elements has had some success…due to the potential damage done to internal organs, as you noted prognosis is grim. I’ve lost some of my most prized fish due to it, including a 6.5 inch-wide mated pair fire red German discus who practically responded to name and would eat from my fingers.