I lost 3 ADFs in 2 days. I have a feeling it's due to a new frog I introduced to the tank a month ago (without quarantine --my bad, I've learned that lesson!). That frog died just over 2 weeks ago. Since then, in the past two days, I've lost my 3 other frogs, two of which I'd had for 2 years, one of which I've had for 8 months. They didn't appear to look funny (bloated, red leg, shreddy skin, etc.). They appeared pretty normal-looking just stiff as boards.
I tested the water with the API kit and everything looks good: 0 for ammonia and nitrite, less than 20ppm for nitrate. My tank's pH continues to be stable at 6.8-7.0. The temp. has been consistently around 75.
I did a 50% water change in my 20g tank, changed my Whisper carbon filter, added a capful of Stability and 4 tsp. of aquarium salt. I've also taken out the almost all the decorations (plastic plants and 2 hiding caves for the ADF's). What is the best way to clean those?
I know I shouldn't use detergent or bleach, but at the same time, I'd like to get any bacteria or whatever off them. Is there anything else I can do to clean the tank if this is a bacterial or fungal thing introduced by the newest frog?
I should mention that I also have 7 cardinal tetras in the tank and they seem completely fine. Also I have a breeder net with 2 one-month-old tadpoles in it. Are the tadpoles doomed? What about the tetras?
I don't have any other tank equipment to put them in right now.
Sorry to be so long-winded. Thanks for any advice you can pass on.