The team, then known as the Media Mantarays, was organized in 2000. They started play in the newly organized
American National Rugby League (AMNRL) the following year, replacing the Pennsylvania Raiders, another Philadelphia-based team that did not make the transition from the United States Rugby League. The team was based in the suburb of
Media, Pennsylvania, and had an affiliation with the Media Rugby Football Club, a local
rugby union club. Like the other clubs, in 2001 they started a team partnership with a club from
Australia's
National Rugby League (NRL), in this case the
Parramatta Eels. With their members drawn from Media RFC, the team found some success on the field. In 2001 they played for the AMNRL championship, ultimately losing to the
Glen Mills Bulls; this would be the club's only championship game. For the 2004 season they relocated to nearby
Ridley Park to play at Catania Park, and changed their name to the Delaware Valley Mantarays after the
Delaware Valley, the area surrounding Philadelphia. After the conclusion of the
2006 season, the Mantarays and the
Philadelphia Fight announced they would be merging to establish a more competitive club the following year. In 2015, a new Delaware club, the Delaware Black Foxes, were formed as an expansion team for the
USA Rugby League. ==Uniform and colors==