Multiple sightings of non-native predator fish have been reported, but the ecological impact of such an invasion remains uncertain.

After the catastrophic floods in Kerala last month that led to massive loss of lives and property, the state is now probably staring at another crisis that is likely to threaten the ecological balance of its waterbodies. Although it is too early to gauge what the ultimate outcome might be, the sightings of predatory, alien fish species in large numbers that appear to have found their way into the state's waterbodies, are turning out to be a cause of concern for the state.

A team of researchers from the University of Kerala, the Kerala University of Fisheries and Ocean Studies, and National Institute of Advanced Studies in Bangalore carried out a quick initial assessment of the state's waterbodies to find 11 alien species in all — four of which are invasive, a report in The Hindu says.

“Globally, floodwaters have proved to be a major route for the spread of invasive species," A Biju Kumar, a professor at the Department of Aquatic Biology and Fisheries, University of Kerala told The Hindu. "Therefore, a precautionary approach is warranted while farming potential invasive (fish) along floodplains.”

The school of alien fish appear to have washed into Kerala from ornamental and commercial fish farms in the state, said an India Times report. Farming certain predator fish species like piranhas are banned in the state, however, commercial dealers continue to rear them illegally.

Some photographs of these non-native fish have been circulated on social media over the past few days. One even shows a few men grinning at their luck after having caught a fish the size of a full-grown human.

Another point of concern, the report cited, is the fitness of some of the foreign species, particularly the species known as the African catfish. This particular type of fish can grow over 50kg in size by feasting on other fish and has no known natural predators.

In the weeks since the flood, the red-bellied piranha — one of the deadliest freshwater fish known to man — has also been reported by fishermen. Another new species spotted in Kerala's newly-calm waters is the Arapaima (pictured), a vicious predator of Brazilian origin known to survive out of water for a considerable amount of time.

While the sightings continue to raise concerns among Keralites, the ecological impact of having a sea of non-native, predatorial fish remains an uncertainty for now.