I had a few hours of down time for my light and i noticed that my blue hippo tang was not acting normally. He was in an unusually hiding spot, at the top of the tank wedged in between the heater and the side of the tank. I didnt find him for an hour or so after i thought he was missing. I moved the heater and he swam beneath a rock where he stayed all day. Worried he was sick, i checked the parameters, everything was 0ppm that should be, ph was fine, but ammonia was .25 ppm. I was headed out the door so i put in ammonia killer and left. I came back and turned the light on, he then swam out like nothing was ever wrong. Has anyone else seen this strange behavior from a tang where he only swims in daylight ?