Just checked my tea tree oil booklet. You can use it for venomous bites, stings, wounds. Usually needs to be applied right away, but I might help to apply after a vinegar dip. It doesn't mention jellyfish though, just scorpions, spiders, snakes and more common bites/stings like wasps and such. It's also useful for pain. I've started using it for my hands and they seem better.

Leslie, I have read that sometimes it can be treated with salt water but I really dont know if it helps or not.....if you try it, just try a small area first.  Poor thing, I hope it gets better soon! 

I thought that was only a problem with frozen or previously frozen fish. Hopefully they are not doing it with fresh fish ! I know I will never handle fish without gloves on again ! Or feed the babies any with skin on.