I have a yellow tang that appears to have gone crazy. First a little background, I'm a complete noob to the hobby, and was somewhat forced into it. My sig. other was recently sold a biorb tank which was set up by the pet store. the tank came with two live rocks, a clown fish, a damsel, and a tang. Though I didn't know anything about marine fish I am a biologist, and could tell that this wasn't a good situation. The tank seems too small for 3 fish. The clown and damsel are small, but the tang is about the size of an adults hand. Since she purchased the tank, I have adjusted the salinity to the about 1.021, and have adjusted the ph. The salinity was low, and the pH was about 7.00 when she bought he tank. I also installed a heater in the aquarium and have it set at about ~78F. In the mean time I bought a 55 g aquarium which I have set up and am currently cycling, I plan to transplant the fish to this tank once the Nitrogen levels are at the right level. Now to the problem. I went to feed the fish this morning, and shortly after adding the food the Tang started swimming rapidly in a frantic matter, butting its head against the substrate, and the rocks in the tank. The tang managed to cut his mouth in the process. At first I though maybe the heater fritzed out and he was being electrocuted, but the other fish seemed ok so I ruled that out. He calmed down after a little while, but I'm worried that he/she(?) might seriously injure himself if he freaks out again. Any idea what could cause such a sudden outburst? Now that I've been hooked into this I look forward to getting the new tank going, but wish I didn't have to enter the hobby in such a manner. I just hope the fish survive long enough to make it into the new tank.