dropsy
Hello, I'm sorry you lost your molly, I'd like to explain a little about dropsy. Dropsy is not a disease,,dropsy is a word to describe symptoms created by various infections. Dropsy can be caused by bacterial infections, sometimes even viruses, tumors, and a few other odds and ends. More often than not it is bacterial in nature and it is the result of a particular fish being stressed for one reason or another. Dropsy in and of itself is NOT CONTAGIOUS, the bacteria that causes it is usally present in the tank and in the fish always,,but because of the fishes' natural immune system and the balance of an aquarium these bacteria are kept in control.
I have dissected many fish that have died from dropsy symptoms. I have frequently found that a bacterial infection has developed from an impacted digestive tract, usually damaged from flake foods. This occurs when too much flake food is fed too quickly, I have found this problem in fish that died for no apparent reason and had no external symptoms.
The best way to prevent bacterial infections,,and any infection for that matter is to do weekly water changes of 10-15 percent,,feed sparingly and keep appropriate fish stocked together.
On a side note,,there are a few concerns with zoonotic illnesses when handling fish with dropsy type symptoms. Often, the agent that is the cause is Mycobacterium, a very bad bacteria that is able to infect humans,,there are many recorded cases of human infection derived from the aquarium, this bacteia takes aggressive antibiotic treatment and there is a very long recovery time. If a fish develops dropsy type symptoms it is best to go ahead and discard the fish,,especially if you have children or elderly people coming in contact with the tank.
But once again, good tank maintenance will usually preclude any infections and just because on fish gets it doesn't mean the rest will.
Also, malefix, tea tree oil, is not an antibacterial agent, it only inhibits bacterial growth,,it does not kill existing bacteia. Bill