107761
In 2004 , 19 northern snakeheads were captured in the Potomac River , and they were later confirmed to have become established ( i.e. , they were breeding ) .
 Potomac River
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 Potomac River