To clarify, the decline of certain Hawaiian fish is in part caused by the aquarium industry over harvesting the fish, but also caused by fishermen overfishing as well and climate change can play a role in the decline of fish populations also. If you remove too many fish, the food chain changes overtime on the reef as well.
Until recently, each commercial aquarium collection permit authorized removal of an unlimited number of fish, and there were no limits on what kinds of fish are taken or how many permits are issued. The battle is still ongoing despite the recent court ruling and don't be surprised if Hawaii places limits on a certain amount of fish to be collected per permit going forward.