Marbled swamp eel

Synbranchus marmoratus

Also known as Muzzled swamp eel

FreshwaterFish

Care at a glance

Temperature: 72–82°F (22–28°C)
pH: 6.0–7.8
Adult size: 39.4 in (100 cm)
Minimum tank: 119 gal (450 L)
Temperament: Aggressive
Social behavior: Solitary
Tankmates: Tankmates with caution
Swim level: Bottom
Difficulty: Difficult
Breeding: No record
Rarity: Rare
Origin: Central and South American wetlands
Family: Synbranchidae

Overview

This is a large, strong, air-breathing eel that must be kept alone, as it is aggressive and will attack or eat tankmates. Treat any companions with real caution: almost anything small enough to swallow will be eaten, and it can injure fish its own size. It lives on the bottom and needs a lid that seals completely, because it is a determined escape artist that can climb out and even cross damp ground. Provide a soft substrate, sturdy hiding places such as pipes and caves, and feed meaty foods like earthworms, prawn, and pieces of fish. A long, heavily built tank of at least 450 liters is a realistic minimum for a fish approaching a meter.

In the wild

The marbled swamp eel ranges across the wetlands of Central and South America, from Mexico to northern Argentina, in swamps, ditches, canals, and slow streams that often run low on oxygen. It copes by gulping air at the surface, so it does not need pristine flow, but it does need secure cover and a soft bottom to rest in. It is adaptable over 22 to 28 C and a pH of 6.0 to 7.8.

Good to know

Synbranchus marmoratus belongs to Synbranchidae, the swamp eels, and can grow to around a meter long. It breathes air through the lining of its gut and mouth, which lets it survive foul water and short trips overland. It is not bred in home aquaria, so captive spawning is essentially unrecorded, though it is known to tend a nest in the wild.

Did you know

When its water dries up, it can burrow into mud and estivate for months, living off its own body reserves until the rains return. A drought that would kill most fish just puts this one on pause.