[Sk8r]

The list of aquatic species it may kill outright:
corals
anemones
invertebrates of all sorts
live rock bacteria
bannerfish
clownfish
lionfish
wrasses
angel fish
sharks
rays
seahorse
dragonets: mandarin, scooter blenny, etc.
jawfish
eels are iffy.

Considerations when using copper:
1. is the species sensitive? if so, look for another med.
2. is the fish in a weakened condition already? Unless copper is the ONLY treatment for the ailment, try to find another med.
3. is the fish already refusing food? Copper depresses appetite.
4. do you have absolute regulation of evaporation in the treatment tank? Evaporation can raise the dosage too high.
5. is there carbon in your filter? Carbon will remove the med.
6. is it a clown with a nem? Once treatment is done, let the clown recover for a week and build back his slime coat: copper strips it, and he could be stung to death by his own nem.

Note that the slime coat is a fish's natural protection against parasites and infection. It functions much like our own outer skin. Once copper treatment is done, take measures to build the fish's general health back up.