Our RES who is about 9-10 months old has not been eating well for the last 4 days. Today he won't take anything. Last couple of days he's only taken a total of 4-5 pellets. He won't bask either. He's active in the water but appears shy it we look at him. He tries to hide under his basking platform.

Any help or information would be greatly appreciated.
Water is clean, no odors. Temperature is a steady 78 degrees.
Thank you