Frecklefin eel (Macrognathus aculeatus) — 10-12cm

Overview

The Frecklefin Eel, scientifically known as Macrognathus aculeatus, is a graceful, nocturnal tropical fish UK favourite that brings unique character and fascinating behaviour to peaceful community aquariums. Reaching up to 6cm in length, this spiny eel is well-suited to tanks of at least 75 litres and thrives in soft, warm water with gentle filtration and a sandy substrate. Available for freshwater fish for sale UK, the Frecklefin Eel is an excellent choice for aquarists seeking an unusual, peaceful bottom-dweller with engaging burrowing habits and striking spotted coloration.

Appearance

The Frecklefin Eel is an elongated, eel-like fish with a streamlined body and distinctive spotted pattern. The base colour is typically tan to brown, adorned with numerous dark spots and ocelli (eye-spots) that create a striking freckled appearance. The dorsal fin runs the length of the body, merging with the caudal and anal fins to form a continuous fringe. The eyes are large and expressive, and the snout is pointed, reflecting the fish's fossorial lifestyle. Overall, the Frecklefin Eel is a beautiful, understated fish that adds visual interest and unique character to planted community aquariums.

Natural Habitat

Native to Southeast Asia, the Frecklefin Eel is found in freshwater habitats in Thailand, Malaysia, Indonesia, and nearby regions. In the wild, these fish inhabit slow-moving rivers, streams, and flooded areas with soft, sandy or muddy substrates and plenty of submerged vegetation. The water is typically warm, soft, and slightly acidic, with gentle currents and abundant cover. Frecklefin Eels are nocturnal and spend much of the day buried in the substrate, emerging at dusk to forage for small invertebrates and insect larvae. Replicating these conditions in the aquarium is essential for the health and well-being of this species.

Aquarium Setup

A minimum tank size of 75 litres is suitable for a Frecklefin Eel. Use a soft sandy substrate that allows natural burrowing behaviour—this is essential, as the eel will spend much of its time partially or fully buried. Plant the aquarium with hardy species such as Java fern, Anubias, and Vallisneria, and include driftwood, smooth rocks, and leaf litter to create hiding places and visual interest. Use a tight-fitting lid with no gaps, as these fish are skilled escape artists and can squeeze through surprisingly small openings. Filtration should be gentle to avoid strong currents, and maintain soft, slightly acidic water with regular small water changes. Subdued lighting will reduce stress and encourage the eel to be more active and confident.

Feeding

Frecklefin Eels are primarily carnivorous, feeding on small invertebrates and insect larvae in the wild. In the aquarium, offer primarily meaty foods such as bloodworms, blackworms, brine shrimp, insect larvae, small crustaceans, and quality sinking carnivore pellets or frozen foods. Feed after lights dim, as this species is most active at dusk and during the night. Use a feeding tube or drop food near the eel's hiding place to ensure it receives adequate nutrition. A protein-rich diet will support health and encourage natural foraging behaviour. Avoid overfeeding, which can lead to water quality issues.

Behaviour

The Frecklefin Eel is a shy, nocturnal fish that spends much of the day buried in the substrate, with only its eyes and snout visible. At dusk and during the night, it emerges to forage for food, navigating the aquarium with graceful, serpentine movements. These eels are peaceful and non-aggressive towards tankmates, though they may eat very small fish or invertebrates. Frecklefin Eels are intelligent and may learn to recognise their keeper, often emerging at feeding time. Their unique burrowing habits and nocturnal activity make them a fascinating addition to peaceful community aquariums.

Tank Mates

Choose tankmates carefully to ensure compatibility with this peaceful, nocturnal species. Suitable companions include peaceful midwater fish of similar size, non-aggressive barbs, danios, rainbowfish, and gouramis. Avoid very small fish, shrimp and other small invertebrates, fin-nipping fish, aggressive cichlids, and large predatory fish. The Frecklefin Eel is best kept in a peaceful community aquarium with fish that occupy the mid-to-upper levels, leaving the bottom area for the eel to forage and burrow.

Breeding

Breeding Frecklefin Eels is uncommon in home aquaria and little documented. Successful spawning typically requires excellent conditioning, mature water quality, and likely seasonal cues such as cooler temperatures or increased water flow. In the rare instances where breeding occurs, the fish lay eggs in hidden areas among plants or substrate. Fry are extremely small and require infusoria and newly hatched brine shrimp. Due to the specific requirements and limited documentation, breeding is generally beyond the scope of most hobbyists.

Why Buy from Tropical Fish Co

Tropical Fish Co is a trusted supplier of best place to buy tropical fish online UK, offering healthy, well-conditioned Frecklefin Eels sourced from reputable suppliers and quarantined for quality assurance. We provide expert guidance on peacock eel care guide, planted tank fish setup, water chemistry, and compatible tankmates to help you create a thriving peaceful community aquarium. With secure packaging, reliable buy tropical fish online UK free delivery, and a commitment to customer satisfaction, Tropical Fish Co makes it easy to buy nocturnal aquarium fish with confidence. Whether you're building your first planted community tank or adding to an established collection, our knowledgeable team is here to support your success.