Wildwood....don't mean to be sarcastic....well i do really but i get bloody annoyed with people who come on here and give out misleading advice to people who don't know better. Frogs have being spawning in ponds full of fish for centuries and most people encourage them into their garden and ponds....i have a 1,000 gallon pond just for fish and wildlife and there's loads of frogs in there. However, the same pond housed some of my koi before i built them a 3,000 gallon pond. I would welcome the frogs in there too but it is difficult for them to get out and i don't wan't them drowning. None of my koi ever succumbed to Trichodina.
Kaztuz's reply above seemed to border on panicking...."OMG...everyone get the frogs out of their ponds as it will wipe the entire fish population out" type attitude and that was totally uncalled for.
As stated in the original question, fish are more at risk this time of year if the male frogs can't find a mate. It's not unheard of for females to have 5 or 6 amorous males clinging to her and in the process, inadvertently drowned her !!! As we've seen, fish can be at risk too although not very common thankfully.
Hope this helps