Great post Adrian!
Several of the books on raising killifish talk about raising greenwater
cultures. They suggest crumpling up a piece of lettuce (or putting it in the
microwave for a half minute) and placing it in your culture container, which
is said to provide nutrients for the culture.
A Chicago killi club member (yo Brad) suggested using some peas instead, as
they have more nutritional value than a romaine lettuce leaf. Makes sense to
me, though I get a nice green culture with the romaine lettuce and a
lightbulb shining on it all day. I use half tap, half aquarium water.
-- Stephen