Red-Eared Slider Turtle

Question
I have a red-eared slider turtle that I have had for about 5-6 months now. His name is Norman and he is an incredibly happy turtle! I have him in a 10 gallon tank as he is only about 1.5in in diameter and I will be moving him into a bigger tank the moment he becomes 2-2.5in in diameter so no worries there. He has a basking rock with the correct lamp (I've had it checked by a pet store and another expert) and loves to bask. He is constantly swimming like a psycho (hence the name Norman after Norman Bates from Psycho the movie, my mom named him haha) and is absolutely one of the most wonderful and happiest pets I've ever owned.

I feed him about 4 hatchling formula sticks dipped in a calcium supplement every morning and usually a few dried shrimp or krill in the afternoon. He also LOVES red leaf lettuce, it makes him go absolutely insane. Because he is so active, he still manages to stay almost a bit underweight so he is starting to get a little more each day, I don't want to add too much too soon since I know this type of turtle is prone to gorging.

Anyway, although he is very active, I am noticing sometimes that he seems quite bored. I catch him trying to nibble on rocks, plastic plants, and especially the Dr. Turtle water conditioner I put in. Although none of these will harm him since they are either too large or hard to consume and simply not a harm, I think he is definitely bored in his tank. I was wondering if there was anything I could get to entertain him? I was thinking maybe some guppies or feeder fish for him to chase but I wasn't sure if he was old enough or if they would simply be too large for him to consume and it would just be torture for them. Sorry this was so long but I like to give a complete history.

Also, if there is anything else I could feed him (like fruit or other proteins) please let me know! I want to make his diet as varied as possible so he is as healthy as possible! thank you!

(Sorry if you received this question multiple times, I've been waiting for an answer for almost 4 days and when I tried to resend it didn't seem to work!)

Answer
Dear Melissa:

I am sorry for the delay in answering your question but I just received it.  It sounds to me like you are on top of your game and Norman is one lucky turtle to have you as a friend.  Everything you are doing sounds great but leave the calcium off a few days at a time, to much is worse then not enough and make sure the basking light is far enough above him so as not to burn him.  Once again, I am sorry for the delay and you are an exceptionally good keeper, keep up the good work and I wish both of you the very best and merry Christmas.

                     Truly yours
                     Joel La Rocque