Heterandria formosa and shrimp?

Heterandria formosa is a livebearer, not a killifish.

I currently have a colony of these fish in a tiny little tank with some cherry and bumblebee shrimps. The females are carrying eggs for several weeks now so as soon as they hatch, any predation will be obvious since it is such a small tank with barely any hiding spaces. I used to keep Endler livebearers with the shrimps, and they would constantly chase the females around, trying to get at the eggs that they're carrying. I have not seen this behavior among the H. formosa so that's encouraging. [smilie=t:

The common name (accepted by the American Fisheries Society) for this fish is least killifish, the smallest vertebrate in North America. The Family Poeciliidae and the Family Fundulidae are in the Suborder Cyprinodontoidei, they are basically the livebearing toothcarps(kilifish). You can check Nelson's Fishes of the World or Parenti's (1981) revision of the suborder.

As to this fish with shrimp, they are way too small to bother any shrimp common in the hobby today. I doubt they would bother juvenile shrimp unless they were molting, in which case cover would be a good idea for the shrimp. I tried to start up my colony again this past summer but, for the over zealous sorting of my fellow collectors, I ended up with none for my effort. Maybe this year will be kinder to me.

Thank you for the correction SCMurphy.

I have since removed my H. formosa from the little tank because these critters actively scavenge every possible crevice looking for food, which include baby shrimps. I've switched them out for some Boraras maculata/brigittae who spend most of their time in mid-water. Even when they do venture to the bottom of the tank, they ignore the baby shrimps.