Mike,
So you've had success treating fish with just water changes in the hospital tank?
I've had little luck treating anything besides ich during my years of fish keeping, so I'll definitely try your approach.
I have a 30 gallon that I use as a hospital tank.
No fish goes into any of my community/breeding tanks - regardless from whom or where I got them - for at least 4, usually 6 weeks. If things just don't seem right, even though the fish are eating normally, they stay there until I feel they are OK. One should have almost no disease problems if a quarantine tank is used. Without a quarantine system your community/breeding tanks are continually susceptible to diseases and parasites every time a new fish is added. That's your choice. Mine is to err on the side of caution. Depending on what medications you use, a small quarantine set-up costs about the same as 2 or 3 treatments of a typical community aquarium. To me a quarantine tank is cheap insurance. The tank doesn't need to be up and running except when needed. Other times it can be stuck in a closet. I see cost and lack of space poor excuses for protecting your fish.
So hot water can be an option to sterilize then. I'll try the airstone+plants floating on my next one. Thanks GeraldEither bleach or hot water (or both) will sterilize it. Keep a few extra sponge filters or box filters with sand running at all times in your healthy tanks, so you always have a spare filter to use for a quarantine tank. Or, you can use fast-growing plants and an airstone, and not bother with a filter in the Q-tank.
BTW - that ram above (2010 pics) looks like classic bacterial infection, and very likely to be Mycobacterium.
For hot water, I feel it is best for the water to be over 180°F/80°C. Even at this temperature there are some pathogens that can survive. This is why a 10% bleach solution is a better option.
I was afraid I'd leave a few ppm of bleach after washing it post-bleaching. Now i know the heavy dose of dechlorinator is the key. Thanks Mike!Why avoid bleach? All a tank needs is a couple of good rinses and a heavy dose of dechlorinator, then it's ready to go.