OK, those photos give me a definite ID. Those are gulf killifish, a species of saltwater killifish which are also adapted at living in freshwater environments. They are highly tolerant of extremes in salinity from pure freshwater to nearly twice the salinity of normal ocean water. Very closely related to the mummichog which is basically its east coast cousin. They sometimes go by the nick name of mud, bull or cigar minnows...
The black spots appear to be mussel glochidium.
