Wild caught sticklebacks and mosquito fish should not be fed because they are natural vectors for several serious parasites. Avoid large quantities of oil laden species such as mackerel, and to a lesser extent smelt and goldfish that are known to induce steatitis. Fish should not make up the majority of aquatic turtles diet except for the mata matas which are fish specialists. Mata matas can be trained to eat whole skinned mice. Chopped or whole baby mice , or chopped, whole, skinned adult mice are eaten readily by many species.
Older mice have more mineralized bone and are an outstanding source of bone for shell growth.
Chopped, whole, skinned, adult mice are one item that can and should be fed in large quantities. Commercial diets such as floating food sticks, tender vittles cat food, gaines burger semi-moist dog food are all fine in moderation. Commercial diets should be soaked until soft before offering them to the turtle. Patience and persistence is required with commercial diets because acceptance can take several weeks. Desiccated insects are nutritionally inadequate and should not be fed.