Were the fry of different sizes? I would be hard pressed to tell differences between Endler's fry and those of "wild-type" guppies. Domestic strains of guppies may drop relatively larger fry.

I applaud you for helping out with your daughter's 4th grade class. (I think I was encouraged to bring turtles, crayfish and other critters to my 4th grade class by a truly remarkable lady.) Hope the fry don't get out of hand. Also hope that the Quicklinks and recent discussions are useful to you.

What part of the country (in a general sense) do you hail from? It is a long shot, but there might be livebearer nuts in your region who could help ID those fish.

In the meantime, for your entertainment and edification, here are a few sites and images which may be of use:

That Newcomb site has a lot of neat info on the Endler's. Since much of that was written, Armando Poul has returned to the lagoons where those fish have been collected. He related his experiences and thoughts in a terrific article a few months back in TFH. Naturally I can't find that article at the moment.

http://members.cox.net/newcomb1/

Somewhere Jbo has some other neat Endler's shots than just at the www.fishiezoo.com site.

I wonder if Scott Lockwood has shots of that strain I sent his way. I can't even remember the name he and others identified it as (other than that old "peas in the pod strain" which was probably from Endler's original collect, which suffered from a founder effect and became just one morph. Peacock strain?

Feral guppies in Hawaii, not exactly like the originals:

http://www.hawaii.gov/dlnr/dar/streams/stream_aliens.htm

Some other looks:

http://www.aquarian.com/cgi-bin/trans.pl/fr/expertise/articles/amazing_guppy01.shtml

http://www.guppy-fish.com/history.html

Shots of preserved male guppies from stream with small and large predators:

http://www.micro.utexas.edu/courses/levin/bio304/popgen/nat.selection.html

A note from a genetic researcher:

http://www.st-andrews.ac.uk/~guppy/people/srussell.shtml