If your fish does not swing its tail fully,
appears to have muscles clamps, rests its head against leaves or the side of the tank or any supports available, it might have listerioses. I placed speakers against the tank and sounded off 377 Hz into the water.
It appears to work. Rife frequencies work on fish and possibly other animals; kills off the germs all the same.
There are other frequencies,
Listeria Monocytogenes, 377, 471, 626, 628, 634, 714, 724, 744, 2162, 7867 Hz
anyone will work. These are the high frequencies that are more penetrating,
Anthrax, Salmonella and Mycobacterium tuberculosis frequencies make the fishes lively but there are no clear indication that the respective germ is being killed.
"If you want to play God, start an aquarium."