Thanks for the paper Steve- I just got to the library and downloaded it for reading at home.

I've suceeded in getting my butlers to take worms and live guppies so far, but I'm looking for other options, and while tadpoles etc. are a no-go, leeches are pretty common around here in 'clean' marshy areas- I could probably trap some with kidneys if the risk of them carrying parasites isn't too great.
I haven't priced leeches out at local bait shops yet- wanted to research risks first.

Honestly I hate leeches. They make me feel 'oogy' just thinking about them,even though I find them fascinating, but if my Butlers go nuts for them I'd be willing to offer them occasionally as a special treat.