I feed mine algea waffers and mazuri pellets. I tried to get them to take other items but it all just ends up making a mess out of my tank, and they often wouldn't even try it. They seemed to like tomatoes and Kiwi more than anything else but even then they would only nibble at it and then leave it. I even tried figs which is supposed to be the staple of many populations diet in the wild and they wouldn't touch it. Algea Waffers and Mazuri seems to be fine, I've had one of mine for 4 years and he grew from just under 4" to about 7" in the first year and half on that diet. No shell deformities or anything. I would recommend feeding either pellets or waffers that provide vitamin D3 since it's hard to give them a shallow basking area in an aquarium and the UV doesn't penetrate the water more than a few inches. This will keep there bones and shell from getting soft. You can also give them a cuttle bone for extra calcium but, but remember that D3 is necessary for calcium absorbtion. Good luck and post some pictures if can.