The Everglades, a vast subtropical wetland, is a unique aquatic ecosystem. Characterized by its slow-moving, shallow “river of grass” flowing from Lake Okeechobee to Florida Bay, it features freshwater marshes, cypress swamps, and saltwater mangrove forests. This diverse mosaic of habitats supports an extraordinary range of life, making the Everglades a globally recognized and important habitat.
Native Freshwater Fish
The Everglades’ freshwater regions support many native fish species adapted to its unique conditions. These fish form the base of the food chain for larger predators like alligators and wading birds.
The Florida Gar is a prominent native, often seen near the water’s surface. This long, slender, predatory fish can grow up to 3 feet, possessing sharp teeth and tough scales. Florida gars breathe atmospheric oxygen, allowing them to survive in poorly oxygenated water and aestivate during dry periods. They inhabit streams, canals, and lakes, often near underwater vegetation.
Largemouth Bass are another well-known native, particularly the Florida subspecies. These sunfish thrive in clear, vegetated lakes, ponds, swamps, and river backwaters. Adult bass are opportunistic feeders, consuming smaller fish, crayfish, and frogs. Various sunfish species, including bluegill, redear sunfish, and the tiny Everglades pygmy sunfish (measuring only about 1 to 1.25 inches), also populate these waters, often found in swamps and vegetated sloughs. The Bowfin, a primitive fish known for its elongated body and ability to breathe air, also resides here.
Native Saltwater and Brackish Fish
The Everglades’ unique hydrological system creates estuarine and coastal areas where freshwater mixes with saltwater, supporting a distinct community of native fish. These brackish environments, like mangrove forests and Florida Bay, serve as nurseries and feeding grounds. Fish in these zones are often euryhaline, tolerating a wide range of salinities.
Snook are a highly sought-after species that inhabit mixed-salinity waters, including estuaries and mangrove forests. Juvenile snook prefer low-salinity to freshwater backwaters for protection, while adults move between estuarine and coastal waters. Tarpon are also common, known for their powerful fights and impressive migrations. While they spawn offshore, tarpon frequently enter the Everglades’ estuarine areas.
Redfish, also known as Red Drum, thrive in brackish and coastal areas, often found in seagrass beds and mangrove edges. Sheepshead, recognized by their distinctive teeth, are also present in these marine and estuarine habitats. Various mullet species are abundant in the Everglades, with some capable of moving far inland through the canal systems. These fish collectively highlight the rich biodiversity.
Non-Native and Invasive Species
The Everglades ecosystem has seen a substantial introduction of non-native fish species, which have become an integral part of its current fish population. More than 50 introduced fish species have established themselves in Florida’s waters, with approximately 26 percent of all fish, reptiles, birds, and mammals in South Florida now being exotic. Many of these species were introduced through the aquarium trade or aquaculture facilities. The extensive network of canals throughout South Florida has facilitated their dispersal.
Peacock Bass (Cichla ocellaris), native to the Amazon River Basin, were introduced to Florida in the 1980s and are now a well-established non-native species. These fish are visually striking and provide a popular sport fishing opportunity. Various cichlid species have also become prevalent, including the Mayan Cichlid (Mayaheros urophthalmus) and Blue Tilapia (Oreochromus aureus). The Mayan Cichlid, first documented in 1983, can tolerate a wide range of salinities and harsh environmental conditions, allowing it to spread throughout freshwater, brackish, and even saltwater environments. Blue Tilapia, originally from Africa, compete with native fish for food and habitat, and their nest-building activities can disrupt native spawning areas.
The Asian Swamp Eel (Monopterus albus) represents another significant non-native species, first observed near the Everglades in 2000. This air-breathing eel, which can grow up to 3 feet long, is a nocturnal predator of shrimp, crayfish, frogs, and other fish. Its ability to breathe air allows it to survive during low water levels and even migrate short distances over land. It has contributed to population declines of native crayfish and small fish in some areas of the eastern Everglades. These introduced species compete with native wildlife for resources and can sometimes carry diseases, altering the ecosystem’s balance.