Oddly the thing that got mine to finally host was I added a snowflake to the tank, which happen to be a tad bigger then my female. This created a war in the tank and basically forced my clown into the nem as a result, although had to remove the snowflake to stop the war, but hey they ended up in the nems and now wont leave them.
Dont recommend doing that though, was a serious pain in the arse