Least killifish are the smallest live bearer in North America. Yes, they are live bearers and reproduce quickly. Excellent for nano tanks. Least killifish enjoy slow moving waters and are extremely hardy. They can withstand temperatures as low as 50 degrees and as high as 90 degrees with the ideal temperature being in the 70's. Least killifish will do well in a community tank or with shrimp. They are friendly and easy to care for.