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.
Keeping anemones in a reef tank can be a challenge if you are not fully prepared.
Cultivating a nano tank can be an exciting challenge but unless you choose the right fish for your tank, you may be in trouble.
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.