Bev,
It sounds like fish keeping is a family affair. That is super!
I have 4 children. (oldest is 21) but did not start the hobby until a few years ago (because of extensive traveling in Europe over 18 years.)
So, only my youngest, now 11 years old has a love for the hobby. He may even be an aspiring marine biologist.

He has a 55 gal. fish only tank. Main interest is to watch fish attack their food at feeding time. It's fun and entertaining. He has 3 that will all grow to 7-9 inches. The lionfish will swim to the tank wall as soon as he sees us peering in, and waits like a puppy with his whole body wagging until we lower the food, then snatches the fish whole. The spotted grouper peers out with big greenish-blue big eyes from a cave we made for him. But is very visable inside the very open structure. He rushes up, snatches and whips back into his cave. The freckled hawk, a perching fish, will swoop up and grab at anything we throw in. They can eat up to 15 silversides between them each day(If we let them) Guests love to see his tank when they come to our house.
You would not want his fish in your tank, as they have aggressive personalities. It seems like a peaceful, relaxing tank is what you have. We have that kind in our family fireplace room. I love my 3 PJ Cardinals who seem suspended in mid to upper tank level and just look interesting with their spotted pajama pants on. They are not territorial. Is your blue tang, clown, or foxface territorial? Do you still have your dottyback and basslet? :confused: I think nothing is worse for a relaxing, peaceful tank, than to see a territorial, aggressive fish bullying everyone around. The hawkfish, even though he has a great personality would probably chase others for the same food source.
If you have been able to maintain a delicate balance of compatiblity, be thankful and cautious in what else you introduce as it could wreck havoc on your tank. Rule of accomodation 1 inch of fish for every 2 gallons of water. In the opinion of one book, it's better to err on the side of too few fish than too many. That is why we have 5 tanks in our house,

2 salt and 3 fresh, to accomodate all the types of fish we like (including, giant oscar cichlids & pirrhana) Continue to closely observe your dear little manderine, as faded colors and discoloration are classic signs of stress. Hopefully if he was injured from the anemone, he'll bounce back quickly from feasting on all those copepods.
Love those fishies,
c-c