I noticed the past 2 days Gimpy was hanging out the the top of the tank, with part of his body above the water line. When I opened the lid, I smelled something disgusting. Turns out my ammonia level had spiked to a little over 1 and the poor thing was trying to get out of the ammonia...So last night I took the tank 1/2 down, today need to get some new carbon, maybe with ammonia chips and after my water change it was down to below .50. Still high, but Gimp was not trying to crawl out of the tank anymore. And what I wanted to bring to everyone's attention, was the abnormal behavior that signaled something was going wrong, hopefully before he suffered any ill affects......Keeping my fingers crossed!