They eat a wide variety of food to get their nutrients. The food they eat are very common and easily available. That include tomato, carrot(grated), water plants (refer to 'housing'), green beans, leafy vegetables, commercial turtle food, fruits, or feeders (meal worms, earthworms, crickets, guppies, water snails ...) But don't feed them too much of crickets, spinach, banana, peas and vegetables from the cabbage family. Commercial food should also be serve as staple food, because it contains much supplement, so don't feed it too much. Frozen food must be thawed before feeding because there's lack of thiamine. Food containing too much fat is also no good, like chicken, beef, cat and dog food... Shrimp should be okay. Also avoid processed food like ham and sausages, and food high in salt content. Vitamins can be fed every fortnight.

Baby turtles may not be able to swallow big chunks of food like feeders and big pieces of meat, so cut the food up for them.

Feed them once or twice a day, and do not throw too much food, estimate how much your sliders eat at a time (15-30 minutes). If you feed them once a day, just feed till they don't want to eat anymore. Giving them excessive food is wasteful and will pollute the water quickly. You can feed them at a specific corner of the aquarium so that the food will not pollute the water too quickly and the turtles can also recognize their feeding area. You can also feed them at a fixed time of the day. So when your turtles keep wandering about at that feeding corner, you know that it might be hungry. Hungry turtle will also be restless and nosing at objects. Sometimes they might beg for more food, don't feed them too many times a day or they will get bloated and fat. I feed my res once a day or once every two day because if I feed them too frequently they will just ignore the food.

When hungry for too long, the turtle will become weak. If food is offered too late, the turtles may not recognize or eat it, even when placed in front of them.

Remember that turtles can only swallow under water. See Interesting Facts.

A healthy slider should grow steadily in size as months go by. Compare their size with objects so that after half a year to see how much it has grown. If your slider did not seem to grow much after one year, consider it's diet. Growing too fast is also no good, as it might deform the shell. So don't overfeed.

If the slider has a poor appetite, find out it's favourite food and mix other food in small quantity with it's favourite food. So that it can get more nutrients. If they refuse to eat, feed them every other day, you might have feed them with too much food to digest.

An obese slider will have the flesh around it's neck bulging out when it draws its head in. If your slider is obese, feed it lesser food and let it exercise more. Too much protein or being too fat may deform the shell of the slider.

If you find that the aquarium gets very dirty after feeding, try to feed them in a separate tub.