I've only been at this for a few years now, still thinking about delving into saltwater tanks.
Sometimes doing nothing is better than anything.
1 Leporinus, 2 Parrots, 9 African Cichlids, 1 freshwater Puffer, 3 Angels, 3 Long Finned Tetras, 2 Plecos, 2 Chinese Algae Eaters, 2 Bumblebee Loaches, 2 Peacock Eels, 1 Danio
Whatever sound my cat made when he jumped up on top of a fishtank, and didn't realize I had the top off until it was too late.
When you see signs of stress in your fish, you can then take steps to identify the source of that stress and then to resolve it before it becomes a major issue.
If you're looking for a unique way to stock your new tank, give freshwater shrimp a try.
If your fish is suffering, you may want to consider euthanasia as an option to humanely end his pain.