According to the Red Ear Slider website, turtles of this species stop eating for a variety of reasons. One common problem is that turtles placed in new environments often become stressed, making them inactive and reluctant to eat.
The appetite of red-eared sliders may also be affected by incorrect water temperature; water should be kept consistently at 75 to 78 degrees Fahrenheit, and the turtle must always be fed while in the water. Pellets are the correct staple for the diet of this species. They must have a strong odor to entice the turtle. Vegetables must also be incorporated into the diet of older turtles because they may refuse pellets alone. Additionally, red-eared sliders do not compensate for previously missed meals, so they may reject items fed in excess.