You may have noticed some new swimmers in the pond. These small, brown fish are not guppies; they are mosquitofish. They are related to guppies, but lack the attractive colors of aquarium fish.
We aren’t sure how they got into the ponds. They may have hitched a ride when we relocated the hardy waterlilies to the Jewel Box this Spring.
The western mosquitofish, Gambusia affinis, is naturally found in the southern parts of the United States, including portions of the Mississippi River system. These hardy fish can survive harsh conditions like muddy, low-oxygen waters.
Mosquitofish have a high rate of reproduction, which causes them to eat more, which causes them to reproduce more. Mosquitofish don’t lay eggs like many other fish. They give birth to baby fish – many, many baby fish. This can lead to overwhelming competition with native species and have profound impact on the foot chain of the pond ecosystem.
Because of the stagnant, poor water-quality environments, these fish developed a taste for the mosquito larva that also grow there. And boy do they eat eat a lot! People introduced them to non-native waters to help control mosquitos – so the name stuck.
Mosquitofish don’t eat mosquito larva exclusively. They also eat the babies of native fish, other fish, and even amphibians!
Although we didn’t invite them, they aren’t harming the Jewel Box ponds.
In environments like these concrete lined ponds, mosquitofish provide a valuable service – namely keeping mosquitos in check. In natural habitats where they aren’t native, mosquitofish are considered pests.
Our caretakers are keeping a close eye on these surprise guests to make sure THEY stay in check
Link to Mosquitofish
The St. Louis Water Garden Society is an organization of pond and water garden enthusiasts in the Greater Saint Louis area who meet to learn play, and enjoy their hobby together.