Nils
Aquarium Advice Addict
I'd personally raise them and keep them alive, but if you really need to euthanize them then do what you want. I've only euthanized one fish before and it broke my heart. I'd put them in water that has been in the freezer for about 15 minutes, that's what i did and he instantly died. If it were me they'd be treated like normal fish and I'd do a lot to keep them alive.