Sorry for the baby frog death; it was a cutie . The CL on water slowly did poisoned him and as you say; the fruit punch bath gave it the final push to death. Time to first work on the other frogs and then sterilize his enclosure.

Don't stress too much; I've accidentally killed a few of my pets. Last was my 2 year old blue crayfish, when moved it to a bigger tank, and added a larger clay pot. The clay pot had been in a fish tank a year before, which had been treated with meds toxic to inverts. Back in water the meds leached out and in couple day he was dead. Took me a while to figure out what went wrong then went .