Protection of the environment now includes strict regulation of the introduction of foreign species. A good example of why we need this restriction is the proliferation of janitor fish in Laguna Bay, Marikina River, and other bodies of water in the Philippines. The janitor fish was released to the wild by aquarium hobbyists who no longer wanted janitor fish that outgrew the other species in their aquarium. Thus, the environment was invaded by an uninvited species.

Vanzi, S. J. (2012, September 9). Sustainability -- key to man's survival. Manila Bulletin, p. J-4.