Home / Fishes / Spiny eels and swamp eels / Asian swamp eel
No federal permit to keepAsian swamp eel
Monopterus albus
Fishes › Spiny eels and swamp eels (Synbranchiformes) › Synbranchidae (Swamp eels)
The Asian swamp eel (Monopterus albus), also known as rice eel, ricefield eel, rice paddy eel, or white rice-field eel, is a commercially important, air-breathing species of fish in the family Synbranchidae.
Care at a glance
Species-specific aquarium care
- Tank: At least 60 in long and 30 in front to back for one adult (adults commonly reach about 15.7 in / 40 cm; the largest recorded was 39.4 in).
- Water: Freshwater (tolerates brackish).
- Temperature: 77–82°F (range recorded for this species).
- Layout: Lives on or near the bottom: floor space and hiding places matter more than height.
- Diet: A predator: feed meaty foods sized to its mouth (frozen fish, shrimp, worms); it will eat tankmates that fit in its mouth. FishBase classes it as a carnivore.
Calculated from this species' own FishBase record: tank size from its typical adult length and swimming zone, water values from its recorded ranges. The group guide below fills in general care.
Care guide
Species care notes
- Tank: a base of at least 71 × 24 in (roughly 171 US gallons); space needed is rated “very large tank”.
- Water: a fairly wide range, from slightly acidic to slightly alkaline, 77–82 °F, pH 6–8, 3–25 dGH.
- Difficulty: Moderate (Seriously Fish rating).
Short excerpts from the species profile:
- Setup: “Provide the fish with plenty of hiding places.”
- Diet: “Feeds on a variety of prey in the wild, including fish, amphibians and invertebrates.”
- Tankmates: “Best kept singly and alone due to its large adult size and piscivorous nature.”
- Breeding: “Has not been spawned in captivity.”
From the Seriously Fish profile for this species, which has the full habitat, maintenance, diet, behaviour and breeding write-up 167
Swamp eels
Applies to most species in this group. Habitat: Monopterus albus and Synbranchus marmoratus inhabit muddy wetlands, ponds and waterways, whereas Ophisternon candidum is restricted to subterranean groundwater in Western Australia. [fg315-asian, fg315-marbled, fg315-cave]. Individual species can differ, so compare with the species numbers above and the linked sources.
Housing & setup
- For surface-dwelling species, provide soft burrowing substrate and sheltered margins or dense vegetation; this recommendation follows their documented natural behavior.
- Leave unobstructed access to the water surface and an air space for air-breathing Synbranchus.
- Secure the lid and every service opening while allowing ventilation: these eels can travel overland and escape uncovered containers.
- Plan adult housing around actual species size: S. marmoratus can reach 150 cm; no validated aquarium minimum is supplied by these sources.
- Use a maintained biological filter and water-quality monitoring; air-breathing ability does not remove the need to control toxic wastes.
Diet
- Earthworms or redworms for M. albus.
- Appropriately sized crustaceans and molluscs for M. albus.
- Small fish and invertebrate prey for S. marmoratus; monitor nighttime feeding.
Social life
- House M. albus singly unless using a managed breeding system: adults are territorial and males can inflict fatal bites. Synbranchus may coexist, but will consume animals that fit its mouth.
Health watch
- Aggression injuries in grouped Monopterus.
- Ammonia/nitrite injury and opportunistic infections: general captive-system risks; family-specific prevalence is not established.
Understanding the animal
About this animal
About this animal
It occurs in East and Southeast Asia, where it is commonly sold and eaten throughout the region. It has been introduced to two areas near the Everglades in Florida and near Atlanta, Georgia.
Quoted from the Wikipedia article “Asian swamp eel” (CC BY-SA 4.0) 174
In the wild
In the wild
From this species’ own FishBase record (habitat, bottom type, water and breeding data), not its family. Good care copies these conditions.1
| Where it lives | Lives in freshwater and brackish water, in rivers and streams, lakes, marshes and swamps, estuaries. Stays near the bottom. Found in hill streams to lowland wetlands. |
| Ground it lives on | Over sand, mud, burrows. |
| Water it lives in | Freshwater / brackish water, 77–82 °F (25–28 °C). |
| Climate | Tropical climate. |
| Wild diet | Hunting macrofauna (predator). |
| Behavior to plan for | Breeding: nesters, paternal parental care. |
What this means for care
- Keep water within its wild range, 77–82 °F.
- Use a soft, fine bottom; it lives over fine sediment in the wild.
- It tolerates or needs brackish water; check salinity needs before setup.
- Parents guard eggs or young, so expect territorial behavior when breeding.
Native climate (measured)
Native climate (measured)
| Warm-season highs | about 89°F (up to 95°F in the hottest sampled areas) |
| Cool-season lows | about 51°F (down to 22°F in the coldest sampled areas) |
| Average temperature | 54–81°F across sampled records |
| Relative humidity | 72–79% on average (driest month about 67%) |
| Rainfall | about 1424 mm a year |
Measured at 328 wild occurrence records sampled against WorldClim 2.1 climate data (1970–2000 averages). Air conditions in the range are ecological context, not enclosure settings: microhabitats such as burrows, leaf litter or basking rocks can be cooler, warmer or more humid.
From the sources
From the sources
Quoted from the matching sections of reputable sources for this exact species. Specialist databases are used first; Wikipedia (community-edited, CC BY-SA 4.0) only fills gaps. Other sources are short credited quotes.
| Overview | The Asian swamp eel (Monopterus albus), also known as rice eel, ricefield eel, rice paddy eel, or white rice-field eel, is a commercially important, air-breathing species of fish in the family Synbranchidae. It occurs in East and Southeast Asia, where it is commonly sold and eaten throughout the region. It has been introduced to two areas near the Everglades in Florida and near Atlanta, Georgia. — Wikipedia (community-edited) |
| Where it lives | Home ranges Population dynamics Growth parameters Max. ages / sizes Length-weight rel. Length-frequencies Mass conversion Recruitment Abundance Life cycle Reproduction Maturity Maturity/Gills rel. — FishBase |
| Behavior | Asian swamp eels are nocturnal predators. — Animal Diversity Web |
| Reproduction | Male builds a large free-floating bubblenest among the submerged vegetation close to the shoreline; eggs are spat into the nest after being laid; male guards the nest and continues to guard the young after hatching till they are on their own. Spawning occurs in shallow water. Sex reversal is completed in 8-30 weeks. — FishBase |
| Lifespan | There is nothing published reporting longevity in the wild for genus, family, order, or class. — Animal Diversity Web |
| Appearance and size | Asian swamp eels are cryptically-colored, usually dark brown or green color. — Animal Diversity Web |
| Biology | Obligate air-breathing; Found in hill streams to lowland wetlands often occurring in ephemeral waters. Adults are found in medium to large rivers, flooded fields and stagnant waters including sluggish flowing canals (, 12693 ), in streamlets and estuaries. Benthic, burrowing in moist earth in dry season surviving for long periods without water (Ref 2686 ). — FishBase |
| History and naming | The Asian swamp eel is a freshwater, eel-like fish belonging to the family Synbranchidae (swamp eels). Some work indicates that the species should be split into three geographical clades or cryptic species, although these were not given systemic names, as the taxonomic synonymy was too complex to sort out at the time. — Wikipedia (community-edited) |
| Conservation | Asian swamp eels might pose a future threat to the environment of Everglades National Park, although preliminary studies reported no deleterious ecological effects in Florida. However, more recent studies in the Everglades do show several species faced precipitous declines after the introduction of swamp eels. — Wikipedia (community-edited) |
Data and studies
The numbers
The numbers
Each bar is what one source reports. Where several sources weigh in, the dashed gold band marks their average.
Adult length
Common length to maximum recorded length. Measured as standard length (snout to the base of the tail, not counting the tail fin). Fish in home aquariums often stay smaller than wild records.
Water temperature
Range the species tolerates in nature; aim for the middle.
pH
Water hardness
Minimum tank footprint
Seriously Fish recommends a tank base of at least 71 × 24 in (about 171 US gallons).
Veterinary & husbandry research
Veterinary & husbandry research
- Prevalence of Gnathostoma spinigerum infection in wild and cultured swamp eels in Vietnam Sieu TP et al., The Journal of parasitology 2009
- Renal acid excretion contributes to acid-base regulation during hypercapnia in air-exposed swamp eel (Monopterus albus) Thinh PV et al., The Journal of experimental biology 2019
- Effects of four types of natural bait on water quality, feeding, growth, and antioxidant enzyme activity of Monopterus albus in a recirculating aquaculture system Yuan Q et al., Frontiers in physiology 2024
- Diversification of Toll-like receptor 1 in swamp eel (Monopterus albus) Rao H et al., Developmental and comparative immunology 2024
Peer-reviewed papers that mention this species alongside captivity, zoos, veterinary care or aquaculture. Some cover several species or mention it only in passing, so check the abstract. See all 29 on PubMed → 170
Sources for this sheet
- FishBase (Froese & Pauly, eds.), version 24.07 Peer-reviewed researchThe global scientific database on fishes, maintained by a consortium of research institutions; every value is referenced.
- Seriously Fish species profiles Experienced keeper or breederLong-running aquarium reference written and peer-checked by experienced fishkeepers and ichthyologists; each profile covers habitat, tank size, water, diet, behaviour and breeding.
- Animal Diversity Web: Monopterus albus Peer-reviewed researchAdded in the 2026 source-checked care-guide review.
- University of the West Indies: Synbranchus marmoratus — Swamp Eel Zoo, university or veterinaryAdded in the 2026 source-checked care-guide review.
- Australian Government: State of the Environment 2021 — Biodiversity, subterranean fauna Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- UF/IFAS: Fish Health Management in Recirculating Aquaculture Systems, Part 1 Zoo, university or veterinaryAdded in the 2026 source-checked care-guide review.
- UF/IFAS: Fish Health Management in Recirculating Aquaculture Systems, Part 2: Pathogens Zoo, university or veterinaryAdded in the 2026 source-checked care-guide review.
- Wikipedia (species article) Community referenceFree encyclopedia; useful overviews with their own citations. Intro text is quoted under CC BY-SA 4.0.
- PubMed (U.S. National Library of Medicine) Peer-reviewed researchIndex of peer-reviewed veterinary, zoo and husbandry research.
- iNaturalist (captive observations) Community referenceCommunity observation platform run by the California Academy of Sciences and National Geographic; observations marked captive show animals living in homes, zoos and aquariums.