Link to public copy of peer-reviewed journal article on pathogens that are transmissible between amphibians and fish:
Christine L. Densmore, David Earl Green, Diseases of Amphibians,
ILAR Journal, Volume 48, Issue 3, 2007, Pages 235–254,
Diseases of Amphibians
After decades of experience in the aquarium hobby, there is absolutely no way I'd let any fish near my frogs. Aquarium fish carry more weird funk than any animal group I've worked with. It is only a matter of time before something nasty jumps into captive amphibian stocks.
Oof so yeah I went into my localish hard-core reptile place and brainstormed with them and I think I'll have to do something more like ankles and a medium ish fish like dwarf rainbows. I'd never heard about the issues with fish and frogs transferring diseases so thank you!