I have been feeding him mostly dandelions lettuce and romaine I tried giving him celery today and he seemed to like it. Still I wonder if it is healthy for him.
Celery is not toxic and it does have some fiber. It is not generally regarded as a great tortoise food, but they can eat some from time to time. The celery tops with the leaves are more nutritious than the stalks.
Are you in Brooklyn (I’m thinking that might be the zip code in your avatar location)? If so, I think you should have access to some good hispanic and Asian markets to increase your food options. Most hispanic markets will sell cleaned opuntia cactus pads, labeled “nopales.” Cactus is excellent tortoise food.