I had two endler males and thought they died a while back. But I was looking at my sump and was trying to see if I needed to clean it and saw an endlers swimming around in the bio-balls. I was like WHAT?? Then, I noticed the other one swimming around and they met up in the bottom part swimming around eating stuff off the bottom and off of the balls. So, I had to take out all the balls in one side out and get my little buddies. I can't believe they made it though the overflow, through the filter, through the tray, through the dry balls, and all the way to the bottom of my sump!! Guess, they are my little troupers. Somehow they were able to get around my filter, guess it was needing to be cleaned and it was more floating so they were able to get under it?? I''m glad I found them.