The carnivorous fish are native to the Amazon River.
They were believed to have entered Kasianka Lake after being dumped there by a local resident tired of keeping them as pets.
It is not clear how many of the fish are living in the lake or how long they have been there.
RFE/RL Belarus, Ukraine, And Moldova Report
SUBSCRIBE For weekly news and analysis on Belarus, Ukraine, and Moldova by e-mail, subscribe to "RFE/RL Belarus, Ukraine, And Moldova Report."