xxBarneyxx
Fish Aficionado
1.5" - tiny little things.
Had a bad day the other day - can I suggest that ANY gaps in the roof/lid are covered up? cloth/tape/perspex, whatever. My female jumped, through a gap that (I presume it was that gap) was about 11mm wide. They're great little fish though huh?
I would second covering your tank, especially if its not very deep. I had a small clown jump through about a 1" square cut out of the egg crate cover (the only spot on the whole tank where there was a gap big enough for it to get through!).