St. Johns

The Florida flagfish, Jordanella floridae, is a cyprinodontid endemic to peninsular Florida in the United States. It lives in shallow, weedy backwaters, marshes, canals and ditches. A long-standing aquarium favourite, it is produced commercially and wild fish are very rare outside the U.S.A. Contrary to many reports it does not dig pits or exhibit extended parental care, and breeds as a fractional spawner like other cyprinodontids.

The least killifish, Heterandria formosa, is a tiny livebearer from the United States, found in heavily vegetated margins of still or sluggish water. The smallest known livebearing fish, it is peaceful but not a community fish in the general sense, as the males reach only 2 cm and many commonly kept species will eat them. It is sometimes confused with the much more aggressive mosquito fish of the genus Gambusia.