Excellent. Thank you. Any experience with this? Is there any drawback if I treat and that is not the problem?
First would be determining the cause of the flashing, as there's many reasons for a fish to do it. Otherwise treating, unless you went through a whole quarantine type regimine, would be just shooting into the dark, so to speak.
I don't know all the things that would cause flashing, but a common cause would be ich, velvet and flukes with ich being the most common, but all having similar treatments, so to answer your question about would treating your fish for it even if if it's not the problem harm it, yes and no. I've read a few anecdotes about copper based treatments reducing the lifespan of some fish, as well as improper dosing can also harm fish. There's other methods, like hyposalinity and tank transfer method that are pretty safe for fish. However, the problem would be to do it properly, you'd have to do it to all your fish, and keep them out of your display for 76 days for ich, 45 for Velvet.
When did you add the fish to the tank?
Same question for the other fish.
Did you quarantine them?
Did you quarantine any and all invertebrates and coral?
Are they displaying any other symptoms, spots, sensitivity to light, swimming into areas of flow, anything like that?
