Spiny Eel (Mastacembelus & Macrognathus spp.) Curious, intelligent and unlike almost any other aquarium fish, Spiny Eels are fascinating bottom-dwelling predators that quickly become the stars of the aquarium. Despite their eel-like appearance, they are not true eels and are renowned for recognising their keepers, exploring every corner of the tank and developing surprisingly interactive personalities. Quick Facts Scientific group: Mastacembelus & Macrognathus species Common names: Spiny Eel, Peacock Eel, Fire Eel, Tire Track Eel (species dependent) Current size: Please refer to the selected size option Adult size: Varies by species from approximately 15 cm to over 90 cm Tank size: 120L+ (larger species require substantially bigger aquariums) Difficulty: 🟡 Moderate Temperament: Peaceful predator Social needs: Depends on species; many are best kept singly or in carefully planned groups Is this for you? ✔️ Perfect if: You enjoy intelligent, interactive fish with unique behaviour. You have a mature aquarium with soft substrate. You appreciate unusual oddball species. You can provide appropriately sized tank mates. ❌ Avoid if: You keep nano fish or shrimp. Your aquarium has sharp gravel. You cannot provide a tightly covered aquarium. You want a fish that remains visible all day. Why choose a Spiny Eel? Spiny Eels are among the most captivating freshwater fish available. Their long, flexible bodies, extended snouts and curious nature often lead people to mistake them for true eels, but they actually belong to an entirely different family of freshwater fishes. Many species spend their day partially buried beneath soft sand with only their head exposed before becoming increasingly active during the evening. As they settle into their environment, they often learn to recognise their keeper and may even feed directly from your hand. Their personalities are every bit as impressive as their appearance. Rather than constantly swimming, Spiny Eels slowly investigate caves, plants and driftwood, making every aquarium feel more natural and alive. Benefits Unique eel-like appearance Highly intelligent and interactive Excellent feature fish for larger aquariums Peaceful with appropriately sized tank mates Fascinating burrowing behaviour Long-lived with proper care Care made simple Temperature: 24–28°C (species dependent) pH: 6.5–7.8 Diet: Carnivorous pellets, earthworms, blackworms, bloodworms, prawns and frozen meaty foods Water: Clean, stable and well-filtered Substrate: Fine sand is strongly recommended to allow natural burrowing behaviour. Setup: Driftwood, caves, plants and shaded hiding places Always provide a tightly fitting lid, as Spiny Eels are excellent escape artists. Select tank mates too large to fit into their mouth. Pairs perfectly with Severums Geophagus Silver Dollars Rainbowfish (larger species) Plecos NTA Insight: "Spiny Eel" describes an entire group of species rather than a single fish. Some species remain around 15–20 cm, while others exceed 90 cm as adults. Before purchasing, always check the expected adult size of your particular species to ensure your aquarium can accommodate it for life. Regardless of species, soft sand and a secure lid are two of the most important ingredients for long-term success. FAQ Are Spiny Eels true eels? No. Despite their appearance, Spiny Eels are not true eels. They belong to their own family of freshwater fishes and have different anatomy and behaviour. How large do Spiny Eels grow? This depends entirely on the species. Smaller species may reach around 15–20 cm, while larger species such as Fire Eels and Tire Track Eels can exceed 70–90 cm. Do they need sand? Yes. Fine sand is highly recommended because many species naturally burrow. Sharp gravel may damage their delicate skin and underside. Will they eat smaller fish? Yes. Spiny Eels are peaceful predators and will consume any fish small enough to fit into their mouth. Can they be kept together? Some species can coexist successfully in large aquariums with multiple hiding places, while others are more territorial. Compatibility depends on the species and available space. What do Spiny Eels eat? They thrive on a varied carnivorous diet including earthworms, blackworms, bloodworms, prawns, frozen foods and quality sinking carnivore pellets. Are Spiny Eels suitable for beginners? They are better suited to aquarists with some experience due to their specialised requirements, escape tendencies and sensitivity to poor water quality. How long do Spiny Eels live? With excellent care, many Spiny Eel species commonly live for 10–15 years, with some larger species living even longer.
