Green Wolf Eel

Green Wolf Eel: The Cave-Dwelling Blenny

The Green Wolf Eel (Congrogadus subducens) is a unique and captivating marine fish often sold under the misleading name "eel" due to its elongated, snake-like body and reclusive behavior. It is actually a member of the family Congrogadidae (Eel Blennies) and is a popular choice for large, predatory marine aquariums.

Native to the Indo-Pacific region, this species is known for its highly variable coloration, ranging from bright olive green to marbled shades of brown, often with iridescent blue or white spots near the head. They are primarily nocturnal ambush predators, spending their day hiding among rocks, caves, or thick coral branches, with only their head exposed.

Despite its intimidating appearance, the Green Wolf Eel is shy and generally peaceful towards tankmates that are too large to be considered prey. It typically reaches an adult size of 16 to 18 inches (40-45 cm) in the home aquarium and requires a secure environment that accommodates its need for substantial hiding spots.

Diet & Compatibility:

• Diet: This fish is a dedicated Carnivore, feeding primarily on small invertebrates and fish in the wild. In captivity, it must be offered meaty foods, including frozen items like krill, silversides, chopped market shrimp, and squid. It can be slow to recognize non-living food and may need to be offered food via tongs until acclimated.
• Feeding: Feed adults every 2-3 days, ensuring they receive enough to maintain their robust body condition. A hungry wolf eel may become more bold and aggressive toward smaller tankmates.
• Reef Compatibility: It is Not Reef Safe. While they will typically leave corals alone, they will consume nearly all ornamental invertebrates (shrimp, crabs, snails) and any small fish that fit into their mouth. They are best kept in a large Fish Only With Live Rock (FOWLR) system.
• Temperament: It is Semi-Aggressive / Predatory. It should only be housed with large, robust, and fast-moving tankmates that are too large to be swallowed. Good tankmates include large angelfish, puffers, and morays. They should not be kept with other Congrogadus species unless in a very large tank or if a mated pair is established.
• Housing Requirements: Provide a deep sand bed and ample rockwork to create multiple, tight-fitting caves. These fish will rearrange substrate to make their preferred home. A tight-fitting lid is essential as they are known to escape.

Quick Facts

• Scientific Name: Congrogadus subducens
• Primary Common Name: Green Wolf Eel
• Other Common Names: Wolf Blenny, Green Wolf Blenny, False Eel, Marine Eel
• Origin: Indo-Pacific (Widespread)
• Max Size: 16-18 inches (40-45 cm)
• Temperament: Semi-Aggressive / Predatory
• Diet: Carnivore (Meaty frozen foods)
• Minimum Tank Size: 75+ Gallons
• Reef Compatibility: No (Will eat invertebrates and small fish)