They got mixed reviews from those raising Betta fry
and killies which especially respond to the movement
of live food in the water column. A drawback for those
fish (and I would think, rainbows) is that overlooked
and decaying brine shrimp, and presumably Cyclop-eeze,
set up conditions where velvet will bloom, endangering
and taking fry before we even realize they are sick.
Frozen Cyclop-eeze seems to be better received by many
fishes. I would only feed it in moderation and where
there was a bottom clean up crew, whether of shrimp,
Corys or a bunch of pond snails.
I get a kick out of killie and rainbow people who go
around cursing the burgeoning population of snails in
their fry tanks.
"Have your fry even gotten velvet when b.b.s. was over
fed?"
"No. What's velvet."
Bill Vannerson wrote a couple of articles on
Cyclop-eeze in the Greater Chicago Cichlid
Association's Cichlid Chatter. He talks in the
following about their origin:
http://www.gcca.net/pdfs/Chatter-Jan-00.pdf
All the best!
Scott