Davy has not eaten for the past two days and refused food today also. He has also stopped roaming around the tank, and has gone back to perching on one rock and staying there.
The only change that has been made in the tank is with the light. The light was heavy in the blue spectrum, probably around 3% white, 5% blue and 10% royal blue. I changed the light to a more balanced 5/5/5 on all channels. He ate after that change, so I did not assume him to be bothered by the lighting change. I've since changed the lights back.
I performed a ~10% water change (5 gallons) the first day he refused food. The second day (yesterday), I got a bit concerned and did a 25% change (10 gallons). I'm not sure what to do now that he refused food for a third day. I tried actually taking the piece of shrimp to him and touching his arm with it, but he just shot water at me.
Does anyone have any ideas what might be going on?