I have 4 res that have all stopped eating. They have'nt eaten in a couple of weeks. I have raised them from babies and they are about a year old now. They have been eating Hikari Turtle pellets since I've had them. The water is fine, 78 deg. and filtered by a H.O.T. Magnum filter. They have both uvb and basking lights. They were devouring food and then all 4 just stopped eating. I tried some lettuce,hot dogs and cat food. they dont show any other signs of being sick. What could be wrong?