A congressman today called for government action following a reported invasion of predatory knife fish in Laguna de Bay, south of Manila that has reportedly threatened the livelihoods of half a million fishermen. Anakpawis lawmaker Rafael Mariano said the knife fish, an ornamental predator usually displayed in aquariums, has created major problems at fish farms on the 90,000-hectare lake. “The government must stop making excuses for its inaction,” he said. “The government must act decisively and concretely to stop the invasion of this alien predator which feeds on local fish species.” A fishermen’s organization said the knife fish had already replaced janitor fish, another predator which formerly threatened native species, adding that it had likely been introduced unintentionally. The leader of the group, Fernando Hicap, said the small fry of the knife fish were penetrating cages and pens, eating up to 90 percent of tilapia and bangus (milk fish) fry stocks. Secretary Neric Acosta, a presidential adviser on the environment and head of the Laguna Lake Development Authority, has previously been quoted as saying the rising population of knife fish was not yet cause for alarm, adding the species was edible and of commercial value. The Save Laguna Lake Movement, an NGO, has argued that knife fish hold a low market value compared to native species. "Although there are buyers, they purchase this fish for five pesos (US$0.12) to 15 pesos (US$0.35) per kilogram,” said the organization’s convener Salvador France. “Not many people are keen to eat this fish because it is carnivorous, exotic and not a staple."