Exotic tilapia and mosquito fish were introduced to aquatic ecosystems in Hawaii and throughout the western Pacific in the early 1900s. Some were intentionally introduced to control mosquitoes, and some were unwanted aquarium pets or escaped aquaculture specimens. Since their introduction, these fish have become well established in wetlands and streams throughout the Pacific, negatively impacting native fish and waterbird habitat. Forest Service scientists monitored exotic fish populations in the Hanalei National Wildlife Refuge and tested the effectiveness of a prototype fish screen designed to keep these fish out of wetland units managed for threatened and endangered Hawaiian waterbirds. As a result, they saw a significant increase in aquatic insect production (native waterbird food) compared to an adjacent unit where these fish were present. The success of the screen resulted in the installation of larger fish screens in other units across the refuge, and land managers are considering using it as a restoration tool for Hawaiian streams.