Travel Book

 

The landscape changes quickly when traveling in Colombo. One minute you are surrounded by skyscrapers, the next you are near the sea, and then near a lake filled with Pelicans. In a suburb near Colombo, there was a lake that I found mysterious and slightly menacing. Lakes like this one are actually essential for wildlife on the island and are true treasures, but are still a disconcerting presence. Even in a lake thought to be safe, it is still possible to imagine that a crocodile might have “walked in” from another distant lake. But what worries most experts are not crocodiles, but invasive fish. For example, it is believed that Alligator gars which grow to be 10 feet long and are native to North America are found in this lake. The clown knifefish native to Southeast Asia, one of the world’s most invasive freshwater fish are also found here. So how did they get here? People purchase it from pet aquariums when they are small, but when the fish outgrows the tank they are released into a nearby lake. Maybe some people get bored with the hobby and release the fish. There are said to be 30 introduced species of freshwater fish in the island's freshwater habitats. However not all are invasive, but the trouble is some really are. It’s odd when you think of it. Some fool releases some fish into an isolated water body, and in no time it is teeming with it because it has no natural enemies. It is found maybe only in that water body for a long time, but when it floods it spreads everywhere else.

The tank cleaner (suckermouth catfish), is the most widely distributed and harmful invasive species in Sri Lanka. It can survive several hours outside water. The knife fish that directly feeds on the lava of other species is the second worst invasive fish. The aggressive Mayan cichlids that attack other fish have spread from a water body in Colombo to several other wetlands. The guppy, native to the Caribbean region which was introduced to feed on mosquito larvae, has become more carnivorous feeding also on amphibian eggs. They are even found in the Sinharaja Rainforest.