Is the heater you mentioned a water heater? If the water temp (not the basking platform temp) is 76 to 78, then that's right on target for a baby turtle.
Have you seen these guidelines on turtle nuitrition? There is a lot of good info on here:
http://www.redearslider.com/index_nutrition.html
On the cichlids - aren't those pretty aggressive fish? Do your turtles have to compete with them for pellets? My minnows really go after the turtle pellets when I feed Spot but he's a lot bigger than they are and he always gets the pellets he's supposed to. If he were very small, though, and the fish were bigger, then I think he might not be able compete. And Vanishing is right - one of these days your turtles will start seeing the cichlids as food.
How's your sick turtle doing today? Have you found a good herp vet to see him?