Actinopteri (ray-finned fishes) > Synbranchiformes
(Spiny eels) > Synbranchidae
Etymology: Synbranchus: Greek, syn, symphysis = grown together + Greek, brangchia = gill (Ref. 45335). More on author: Bloch.
Environment: milieu / climate zone / depth range / distribution range
Freshwater; brackish; demersal; potamodromous (Ref. 51243); depth range - m (Ref. ), usually - m (Ref. ). Subtropical; 22°C - 34°C (Ref. 36880)
Central and South America: Mexico to northern Argentina.
Size / Weight / Age
Maturity: Lm ?  range ? - ? cm
Max length : 150 cm TL male/unsexed; (Ref. 79717); common length : 50.0 cm TL male/unsexed; (Ref. 35237)
Morphology | Morphometrics
Body cylindrical and long; eyes small; dorsal and anal fins vestigial (Ref. 26543).
Anguilliform, has no pectoral and ventral fins; its dorsal and anal fins are vestigial (Ref. 27188). Adults inhabit streams, ponds, canals, drains, rice fields, both clear and turbid water (Ref. 11225). Nocturnal (Ref. 11225). Carnivore (Ref. 26543). The male guards and builds nest or burrow (Ref. 205). A protogynous hermaphrodite (Ref. 55367). Its being a facultative air-breather (Ref. 1468) explains, at least in part, why it is often missing from faunal inventories. At the start of the dry season when there's a decline in water level, it digs a tubular burrow in a bank or on the bottom. This burrow, which is for the most part sub-horizontal , can have several diverticula, followed by a vertical section which leads to the exterior by only one opening. Although breathing is slowed down, the fish remains active and flees if it is disturbed (Ref. 27188).
Life cycle and mating behavior
Maturity | Reproduction | Spawning | Eggs | Fecundity | Larvae
A diandric species having both primary and secondary male developmental pathways. Length at sex change = 34.0 cm TL (Ref. 55367). Also Ref. 35344, 103751.
Kullander, S.O., 2003. Family Synbranchidae (Swamp-eels). p. 594-595. In R.E. Reis, S.O. Kullander and C.J. Ferraris, Jr. (eds.) Checklist of the Freshwater Fishes of South and Central America. Porto Alegre: EDIPUCRS, Brasil. (Ref. 79717)
IUCN Red List Status (Ref. 124695)
Threat to humans
Fisheries: commercial; aquarium: public aquariums
Estimates based on models
Phylogenetic diversity index (Ref. 82805
= 0.6250 [Uniqueness, from 0.5 = low to 2.0 = high].
Bayesian length-weight: a=0.00098 (0.00058 - 0.00163), b=3.10 (2.95 - 3.25), in cm total length, based on LWR estimates for this species & (Sub)family-body (Ref. 93245
Trophic level (Ref. 69278
): 2.8 ±0.51 se; based on food items.
Resilience (Ref. 120179
): Very Low, minimum population doubling time more than 14 years (Preliminary K or Fecundity.).
Vulnerability (Ref. 59153
): Very high vulnerability (83 of 100) .
Nutrients (Ref. 124155
): Calcium = 54.7 [22.1, 150.7] mg/100g ; Iron = 1.25 [0.63, 2.74] mg/100g ; Protein = 17.8 [15.6, 20.0] % ; Omega3 = 0.445 [0.210, 0.920] g/100g ; Selenium = 43.3 [16.0, 105.0] μg/100g ; VitaminA = 11.3 [2.5, 51.4] μg/100g ; Zinc = 0.788 [0.436, 1.407] mg/100g (wet weight);