There's something fishy going on in Powai lake: Foreign fish making a meal of their native cousins

Powai lake is host to schools of foreign fish and reptiles.

This is not a bad thing, say fish experts, unless these species start consuming native fish. Some of the growing number of foreign fish that experts have found in the lake include the Piranha, African Catfish, Arowana, Flowerhorn, Red-Eared Slider Turtle plus a few others.

“These fish threaten the existence of our own indigenous species by either devouring them or competing with them for resources. At first there were around 35 native fish species in Powai lake, now there are only around 20,” says naturalist Vijay Awsare..

The milder native species don’t stand a chance against the African Catfish’s strength or the Piranha’s voracious appetite. These alien fish have found it easy to adapt to the Indian environment as most of them thrive in warm tropical climates.

A visit to the aquarium shops outside Kurla East or to the infamous Crawford Market helps find an answer to how they found their way to Powai lake. Sold at Rs100 a pair, the two-inch Piranha are not considered as exclusive as the baby Arowana that comes for a princely Rs750.

Shopkeepers are quick to mention that the fish are not imported, “They’re the Indian Pacu Piranha from Kolkata,” they point out. Pacu Piranha is a cousin of the original red-bellied Piranha, and exhibit the same appetite for meat.

The Red-Eared Slider Turtle is the most commonly bought pet turtle in the world. It is of American origin and is another example of an invasive species.

The inspiration behind comic book heroes Teenage Mutant Ninja Turtles, it is banned in many countries, including Australia, as it tends to enter the ecosystem and outdo or overtake local indigenous species.

Many Red-Eared Sliders are rescued regularly from ponds and lakes around Mumbai, primarily because of people abandoning them as they outgrow the fish tank.

Recently, a consignment of 10,000 of these turtles was seized as it was being smuggled into Kolkata. If they escape into our environment, they will likely wipe out the entire native species of turtles.

Aquaculture (essentially fish farming, of the African Catfish and the Tilapia) has its benefits if carried out in controlled environment. But the rise in illegal fish farms has led to these species escaping into the environment. These are on the International Union for the Conservation of Nature’s list of top Invasive species.

“It is necessary to restrict and regulate aquarium trade and fish farms to check the flow of invasive species entering our ecosystem through illegal entities.

There is no doubt that some of of our indigenous species have decreased in numbers. This issue hasn’t been explored much by us and a lot of education on this topic is required for us as well as the masses,” says Dr WS Lakra, director of the Central Institute of Fisheries Education.

As aquariums and fish become more and more popular, the more illegal trade and fish farming will gain ground. Experts forecast that this will eventually reach a point where it would be difficult to extricate such species from the environment even as they destroy it from the inside.