--- title: "Rice Field Eel: The Invasive Swamp Eel in Florida" url: https://thesea.org/rice-field-eel/ date: 2026-11-13 modified: 2026-11-13 lang: en author: "Blane Perun" description: "TheSea.Org▸Eels▸Rice Field Eel Rice Field Eel — The Air-Breathing Asian Swamp Eel Loose in Florida's Canals Eels By Blane Perun November 13, 2026 9 min read What is a ricefield..." categories: - "Eels" word_count: 2103 --- # Rice Field Eel: The Invasive Swamp Eel in Florida [TheSea.Org](/)▸[Eels](/eels/)▸Rice Field Eel # Rice Field Eel — The Air-Breathing Asian Swamp Eel Loose in Florida's Canals Eels By [Blane Perun](/about-blane-perun/) November 13, 2026 9 min read What is a ricefield eel? The ricefield eel, or Asian swamp eel (*Monopterus albus*), is an air-breathing freshwater fish from East and Southeast Asia that looks like an eel but belongs to a different order, the swamp eels (Synbranchiformes). It has been introduced to Hawaii, Georgia and Florida, where it lives in canals and marshes and is treated as an invasive species. Quick facts Scientific name**Monopterus albus** (species complex) Other namesAsian swamp eel, rice eel, white rice field eel FamilySynbranchidae — not a true eel SizeCommonly 40–60 cm; up to about 1 m Native rangeChina, Korea, Japan, Southeast Asia, parts of South Asia BreathingGulps air; can survive out of water in moist mud In the USHawaii, Georgia, Florida, and isolated northeastern records Florida first found1997 Florida has a long list of animals that don't belong here, from lionfish on the reefs to pythons in the Everglades. The rice field eel is one of the quieter ones. It's a brownish, slimy, eel-shaped fish that spends its days hidden in mud and vegetation, comes out at night to hunt, and can breathe air well enough to survive drought by burrowing. Most people who see one assume it's a native eel or a snake. In this guide I'll explain what it is, how to tell it apart from the American eel, how it got to Florida, and why wildlife agencies want to know when someone finds one. Is the rice field eel a real eel? No. It's a swamp eel, a separate group of fish that evolved an eel-like shape on its own. True eels belong to the order Anguilliformes, which includes morays, congers and freshwater eels such as the American eel. The rice field eel belongs to the order Synbranchiformes, family Synbranchidae, the swamp eels. The two groups aren't closely related. They look alike because a long, finless body is a good design for squeezing through mud, roots and burrows. It's the same reason the [electric eel](/electric-eel/), a knifefish, ended up with an eel's name. If you want the full list of eel look-alikes, our [eel facts](/eel-facts/) page has it. There's also a naming wrinkle. Genetic studies have shown that what was long called *Monopterus albus* is really a complex of several closely related lineages, and some of the swamp eels in Florida turned out to be different from those in Georgia. For practical purposes, people call them all Asian swamp eels or rice field eels. What does a rice field eel look like? A smooth, tube-shaped fish with a blunt head, tiny eyes and almost no fins. Rice field eels are usually olive-brown to dark brown on the back, often with small dark speckles, and paler, yellowish or orange-tinted underneath. They have no pectoral or pelvic fins, and the dorsal and anal fins are reduced to low, skin-like ridges near the tail. The skin looks scaleless and is coated in mucus. The eyes are small and covered by skin. The most useful feature is underneath: instead of gill openings on each side of the head, they have a single crescent- or V-shaped gill slit across the throat. Adults commonly run 40 to 60 cm, and large ones reach about a metre. They're nocturnal, and during the day they hide in burrows, mud or thick plants along the edges of canals, ditches, ponds and marshes. | Feature | Rice field eel | American eel | Electric eel | | ------- | -------------- | ------------ | ------------ | | Order | Synbranchiformes (swamp eels) | Anguilliformes (true eels) | Gymnotiformes (knifefishes) | | Pectoral fins | None | Yes, small | Yes, small | | Gill openings | One slit under the throat | One on each side | One on each side | | Fins along body | Reduced to low ridges | Long dorsal and anal fins joined at tail | Long fin along the belly | | Breathes air | Yes | Can absorb some oxygen through skin | Yes, must surface | | Native to Florida | No | Yes | No (South America) | How it breathes air and survives drought Its gills are weak, so it relies on air gulped at the surface. The rice field eel's gills are reduced, and it gets much of its oxygen by gulping air and absorbing it through the lining of its mouth and throat, which is richly supplied with blood vessels. That lets it live in warm, stagnant, low-oxygen water where many native fish struggle, including flooded rice paddies, which gives the species its name. It can also survive out of water for long periods if it stays moist. When ponds and ditches dry out, swamp eels burrow into the mud and wait for the water to return, and they can wriggle overland on wet nights to reach new water. Those abilities make them tough to eradicate. Draining a pond doesn't necessarily kill them, and they can move between disconnected water bodies on their own. How rice field eels reproduce They start life as females and can become males, and the males guard the nest. Rice field eels are protogynous hermaphrodites. Most begin adult life as females, and older, larger fish often change into males. In its native range the species breeds in the warm season. Males build floating nests of bubbles among vegetation at the water's edge, and the eggs are laid in the nest. The male then guards the eggs and young fry, an unusual level of parental care for an eel-shaped fish and very different from how true eels reproduce. True eels drift their eggs into the open ocean and never see their young, as we explain in [how eels reproduce](/how-do-eels-reproduce/). How the swamp eel got to Florida Most likely through the live food and aquarium trades. Asian swamp eels are a popular food in China and Southeast Asia, where they're sold live in markets, and they've also been sold as aquarium fish. Biologists believe the US populations started from fish released from those trades. Swamp eels were established in Hawaii by around 1900. In the 1990s they turned up in the Atlanta area of Georgia, and in 1997 they were found in Florida, with populations later documented around Tampa and in Miami-Dade County, including canals close to Everglades National Park. Isolated populations have since been reported in the northeastern United States as well. In South Florida, the main concern is the Everglades. The canals near Homestead connect, directly or indirectly, with the marshes of the park, and a predator that can live in low-oxygen water, move overland and survive dry seasons in mud is a real worry for native fish, frogs and invertebrates. The US Geological Survey tracks sightings through its Nonindigenous Aquatic Species program, and Florida biologists have studied the canals to understand how fast the eels spread. ~1 mMaximum length of a rice field eel 1997First found in Florida 1Gill slit, under the throat What do rice field eels eat? Almost anything small enough to swallow. Rice field eels are nocturnal predators that hunt along the bottom and among plants for small fish, crayfish, shrimp, frogs and tadpoles, worms and insect larvae. They are generalists, which is one reason they can establish themselves in so many different habitats. In Florida, biologists worry about the pressure they could add to native species that already face competition from other introduced fish. For comparison with true eels, see [what eels eat](/what-do-eels-eat/). What to do if you catch one Don't release it, and report it. Anglers in South Florida and around Tampa occasionally catch rice field eels on worms or small baits, or find them in cast nets. If you think you have one, take clear photos of the whole fish and the underside of the head, note where you caught it, and report it to the Florida Fish and Wildlife Conservation Commission (FWC) or through the USGS Nonindigenous Aquatic Species database. Don't move it to another water body. Releasing non-native fish is illegal in Florida, and moving swamp eels is exactly how they spread. If you're not sure whether you have a swamp eel or a native American eel, the quickest check is the pectoral fins and the gill openings. The American eel has small pectoral fins behind the head and a gill opening on each side. The rice field eel has neither pectoral fins nor side gill openings. Our page on [freshwater eels](/freshwater-eels/) covers the native species you're likely to meet in Florida. My take Florida's invasive species problem almost always starts with a release: an aquarium fish that got too big, a live food animal set free. I've spent decades keeping fish in aquariums, and the rule I'd pass on is simple. If you can't keep an animal any longer, find it a new home through a store, club or rehoming programme. Never let it go in a canal. Rice field eel as food A popular dish in Asia, but not something to harvest casually in Florida. In China, Vietnam, Thailand and elsewhere, rice field eel is a common food, often stir-fried, braised or cooked in soup, and it's also farmed. That demand is one reason live swamp eels have moved around the world. In the United States, swamp eels from the wild can carry parasites, including nematodes that can infect people if the fish is eaten raw or undercooked, so they should never be eaten without thorough cooking. Food safety aside, the priority with an invasive species is to report it and remove it, not to start a fishery that might give people a reason to spread it further. For eating true eels, see [can you eat eel](/can-you-eat-eel/). Why invasive swamp eels are so hard to control Almost every tool managers use on invasive fish works poorly on this one. Fish poisons such as rotenone work by interfering with how fish take oxygen from water through their gills, and an air-breathing fish that can sit at the surface gulping air, or hide buried in damp mud, is much less vulnerable. Draining a pond leaves swamp eels alive in the sediment. Electrofishing and traps catch some, but the eels spend the day hidden in burrows and dense vegetation, so they're hard to find and count. And because they can move overland on wet nights, a population that is wiped out in one ditch can be re-established from the next one over. That's why the emphasis in Florida has been on early detection, research into how the eels spread through canal systems, and stopping new introductions. Once a species like this is established in a large connected wetland, eradication is unlikely. The goal becomes keeping it out of places it hasn't reached yet, which depends heavily on anglers, boaters and aquarium keepers reporting what they find and never moving fish between waters. Frequently asked questions Is the rice field eel a true eel? No. It belongs to the swamp eels (order Synbranchiformes), not the true eels (order Anguilliformes). The eel shape evolved separately. Where are Asian swamp eels found in Florida? Populations have been documented around Tampa and in Miami-Dade County, including canals near Everglades National Park. Check the USGS Nonindigenous Aquatic Species database for current records. Can rice field eels live out of water? For long periods if kept moist. They breathe air and can survive drought by burrowing into mud. Are rice field eels dangerous? Not to people, beyond a possible bite when handled. The danger is ecological: they compete with and eat native wildlife. How big do rice field eels get? Commonly 40–60 cm, with large individuals reaching about 1 m. What should I do if I catch a swamp eel in Florida? Do not release it elsewhere. Photograph it, note the location and report it to FWC or the USGS Nonindigenous Aquatic Species program. How do I tell a rice field eel from an American eel? The American eel has pectoral fins and a gill opening on each side of the head. The rice field eel has no pectoral fins and a single gill slit under the throat. Sources & further reading - U.S. Geological Survey, Nonindigenous Aquatic Species fact sheet: *Monopterus albus*. - Collins, T. M., Trexler, J. C., Nico, L. G. & Rawlings, T. A. (2002). Genetic diversity in a morphologically conservative invasive taxon: multiple introductions of swamp eels to the southeastern United States. *Conservation Biology* 16: 1024–1035. - Florida Fish and Wildlife Conservation Commission, Asian swamp eel nonnative species profile. - Froese, R. & Pauly, D. (eds.). FishBase: *Monopterus albus*. Continue reading More from Eels [EelsElectric EelAnother "eel" that isn't one. ](/electric-eel/) [EelsFreshwater EelsTypes, ranges and Florida species. ](/freshwater-eels/) [EelsReef EelsMorays, garden eels, snake eels and congers. ](/eels/) BP Last updated November 13, 2026 Written by Blane Perun Blane Perun has been exploring Earth’s oceans and marine life for over 25 years. Founder of TheSea.Org in 1999, underwater photographer, coral aquaculture pioneer, and explorer of 80+ countries. [About Blane Perun →](/about-blane-perun/) [More on Eels →](/eels/)