Thanks RTR and Sumpinfishy. Interesting points, I have noticed that when the temperature has dropped to 79-80 degrees that the monos seem to be less agressive and there apprears to be less nipping. The temperature in the tank ranges from 79 and 83 degrees, usually staying between 80 and 82. Unfortunately the temperature in my tank is very hard to keep on the low side without the apartment getting too cold. Regarding the amount of light , this is another problem since it is already on the low side with a single 30 watt bulb lighting the tank. They are going into the 120 in a couple of weeks so hopefully this problem will not last much longer.