Well your doing alright. I would definetly suggest a much larger aquarium in the near future. But with the setup you have I would add a basking light, and a filter since you didnt mention that in your post. I guess since its such a small tank you could just do routine water changes like 3 times a week instead. Up to you... Make sure the water temp is in around 78 and the basking temp is around 85-95 degrees. Then I would change up the diet. Raw beef and shrimp arnt the best. I would stick with a good commercial pellet like Reptomin or Mazuri as a staple, then some feeders like rosies (fish), and crickets three times a week. You can feed them some shrimp but I would just use it as kind of a snack. They may also eat some veggies like romaine lettuce or aquatic plants like Anacharis. But since there so young they may not, usually they start eating greens when they get a little more mature. Still good to have some Anacharis in the tank though. Helps keep the water clean besides offering them something to munch on...
-Chris
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Currently in the US Navy so I have sold off my collection. But over the years I have had dozens of turtles, fish, geckos, and other lizards. Cant wait to get back in the hobby once im out though!