I have a 30 gallon reef tank that has been set up for almost 3 months now. Everything has been doing extremely well, until this evening. I had to go downstairs to get a drink, and upon glancing over at my aquarium, I noticed that one of my percula clowns was laying on its side at the bottom of my tank. I turned a light on in an adjacent room (so not to overly stress the fish) and saw that my other percula clown was swimming almost vertically. I tested water parameters, and everything showed up normal (ph 8.3, ammonia-0, nitrate-slight trace, water temp 78, SG-1.023). When I watched for a bit, the female clown started swimming into the aquarium walls wildly, up and down, while the other percula swam under a rock. My yellow-tail damsel (left over from cycling) came out of its hole, almost white, and did the same thing-swimming about wildly. I havent added anything other than a sailfin blenny about a week ago, and it doesnt seem to be acting odd. The strange thing about it was that not 2 hours before, everything was going well and all the tank inhabitants were fine. I dont know what to do or where to start, as I am fairly new to marine aquaria, so your help is greatly appreciated.