Blennie question

[kbauer]

I have what I thought was a lawnmower blennie but after doing a search on this board found that it may be a "molly miller" because I can't keep it in the main tank! First it went over the overflow and got caught in a filter bag that I had on for a few days. I thought my new blennie had disappeared and died, then when I went to clean the bag--it moved! 8O She had been in that bag for at least 3 days! Put her back in the main tank--next day went over the overflow again and down in the sump where I have left her. It's been a month now and she seems to be happy down there. Has anyone ever left a fish in the sump? or should I try again in the main tank? Thanks for any advice.