How much do i feed my tortoise

[BirdieF18]

Hi i am just wandering how much i should feed my four year old horsfield she is normally give two small feeds one in the morning which she has while i am gone and one at night when i get home. Is this enough for a growing tortoise. I thought i was right from what i had read but i got told by the man who used to have her it would upset her stomach (Although he didn't seem to knowledgeable as she was kept in a tiny fish aquarium sort of thing). Is he talking sense or rubbish.