Spiny Eel

Adults reach 38 cm in the wild, while in the aquarium they usually grow to 20–35 cm. This fish has a long, snake-like body and an elongated, pointed head. The pelvic fins are very small and short. The dorsal and anal fins are located closer to the tail and merge with it, forming a single large plane. The coloration varies from yellow to light brown tones, sometimes with thin vertical dark stripes. A characteristic feature is a thin light stripe running from head to tail, as well as large black spots with light edgings on the posterior part of the body. The dorsal fin is equipped with sharp spines, which gave the fish its name — Spiny Eel.

This species is widespread across South and Southeast Asia — from India, Nepal and Bangladesh to Myanmar, Thailand, Malaysia and Indonesia. It is found in both fresh and brackish waters, preferring areas with slow currents and soft substrate. In such environments, eels typically burrow into the substrate, waiting for prey to swim by.

Young individuals can be kept in groups, but as they mature, they begin to exhibit territorial behavior, so it is better to keep them individually. Despite being predators, the Spiny Eel is safe for fish that are large enough not to fit into its mouth. Suitable tank mates include Gouramis, Acaras, Loaches, Armored Catfish, as well as peaceful American Cichlids and similar fish.

Macrognathus aculeatus is not very active, preferring to remain in one place for long periods. An 80 L aquarium will be sufficient for a single specimen. When setting up the aquarium, the choice of substrate plays a key role: it is recommended to use soft, coarse sand that will not compact. Other decorative elements, including plants, are chosen according to the aquarist's preferences. Maintaining high water quality is critical for carnivorous species that produce a lot of waste. Therefore, a powerful filtration system is essential, as is weekly water changes of 20–25% and regular aquarium cleaning.

In its natural habitat, Macrognathus is an ambush predator whose diet consists of small fish and crustaceans. In a home aquarium, it readily accepts pieces of fresh or frozen fish meat, shrimp, mollusks, as well as earthworms and bloodworms. Additionally, specialized dry foods high in protein, designed for bottom-dwelling fish, such as flakes or granules, can be added to its diet.

Successful attempts to breed the Spotted Spiny Eel in home aquariums have not been recorded at the time of writing this article. It is known that in their natural habitat, changes in the environment with the onset of the rainy season trigger spawning. These eels can lay up to 1000 eggs, usually at the base of aquatic plants. The incubation period is 3 days, after which the fry begin to swim freely. It is worth noting the poorly developed parental instincts of these fish, which often leads to adults preying on their own offspring.

This fish species is extremely sensitive to water quality parameters. Deterioration of keeping conditions inevitably affects their health, making them vulnerable to various diseases.

When purchasing a spiny eel, it is important to carefully inspect the fish's skin. Individuals often have injuries sustained during transportation, which quickly become infected with fungus. Avoid specimens with whitish growths, open wounds, or signs of emaciation. A healthy fish should be active during twilight hours, but during the day in the store, it may be reclusive or buried in the substrate. — check the integrity of the fins and the absence of damage on the body; — ensure that the fish has no signs of fungal infections or white spots; — ask the seller if the individual accepts frozen foods, as adaptation to a non-live diet can be difficult; — prefer individuals that appear well-fed and do not have a sunken belly.