The city of Sochi, Russia erected a fish statue costing about $3,800 in honor of the gambusia
(aka the "mosquito fish"). In the early 1900s, the fish species were purposefully introduced to the area to fight the infestation of malarial mosquitos, and it worked. There have been no cases of malaria among Sochi residents for over 60 years.
Photo courtesy of Nadiva85 / wikimedia @factsweird