I just took the fish I had in my sump for 3 months out today. I had no idea he was still in there. Before I had my 300 gallon up, I set up my sump with cycled tank water and a whisper 10i and let it run. I have a creek behind my house and scooped out a fish from it and tossed it in my sump to help the bio. I eventually got the tank up and running and forgot about him. One day I remembered and looked, but couldnt find him. I figured he died.
Today I was taking the carbon out of my sump and saw this little thing swimmin around. I laughed pretty hard. He's now in the 300 gallon tank. I have no idea what kind of fish it is. He's a cute little bugger though