One of the questions left unanswered in my article Fish or Foul? was whether the northern snakehead fish found in different locations around DC--Wheaton, Md.; Crofton, Md.; and the Potomac River south of the District--were related. According to the Proceedings of the Biological Society of Washington, they are not. Read the paper here:
http://www.fws.gov/northeast/marylandfisheries/pbsw_b118_02.407-415.pdf