Acanthopsis choirorhynchus

The Horseface Loach, also known as the Long-nosed Loach or Banana Fish, is a fascinating bottom-dweller named for its distinctively long, horse-like snout. Its most famous behavior is completely burying itself in the sand with only its eyes showing. This is a natural way for it to feel safe and rest. Because of this, a soft, fine sand substrate is absolutely essential in its aquarium; gravel or sharp sand will injure its delicate face and barbels, leading to infections.

These are not solitary fish. They are social and feel stressed when kept alone, so a group of at least five is necessary to see their natural, active behaviors. When comfortable, they will playfully chase each other and explore the bottom of the tank. An aquarium for a Horseface Loach must have a tight-fitting, secure lid. They are surprisingly powerful and are known to be skilled escape artists, capable of jumping out of the smallest gaps.

As a bottom feeder, its diet should consist of foods that sink. High-quality sinking pellets and wafers make a good staple, supplemented with treats like frozen or live bloodworms and brine shrimp. They are generally peaceful and can be kept with other calm fish that occupy the middle and upper levels of the tank, such as rasboras and tetras. Due to its specific sand and group requirements, it's best for aquarists with some experience.

Known scientifically as Acanthopsis choirorhynchus, the Horseface Loach is a highly specialized benthic fish prized for its unique morphology and engaging behavior. Its body is elongated and laterally compressed, but its most defining feature is the prominent, fleshy rostrum that gives it its common name. This snout, along with sensitive barbels around its mouth, is used to sift through substrate to find food. Like other members of the Cobitidae family, it possesses sharp, erectile sub-orbital spines that it can deploy for defense. Aquarists should be cautious when netting these fish, as the spines can easily become entangled.

The most critical aspect of its care is replicating its natural fossorial (burrowing) lifestyle. A deep substrate of at least 2-3 inches (5-7 cm) of fine, soft sand is a non-negotiable requirement. This allows the loach to exhibit its signature behavior of completely burying itself, which is vital for its security and well-being. Sharp-edged sand or gravel must be avoided at all costs, as it will cause physical damage to the snout and barbels, leading to stress and secondary bacterial infections.

Their classification as a 'plant rooter' means they are constantly digging and sifting, which will uproot delicately planted flora. Therefore, aquascaping should feature robust, epiphytic plants like Anubias, Java Fern, and Bucephalandra attached to driftwood and smooth rocks. This setup also provides the shaded areas and hiding spots they appreciate. Efficient filtration is necessary due to their moderate waste production, but the filter outflow should be diffused with a spray bar to maintain the preferred low-flow conditions across the substrate. A securely sealed, heavy lid is mandatory, as these loaches are notorious 'tank escape artists' and will exploit any available gap.

In terms of diet, they are omnivores with a strong preference for invertebrates. A varied diet is essential for long-term health. A high-quality sinking pellet or wafer should form the base, but it must be supplemented frequently with meaty foods. Frozen or live bloodworms, daphnia, tubifex, and brine shrimp are all excellent choices that encourage natural foraging behavior. Being primarily crepuscular and nocturnal, feeding is often best done in the evening as the lights dim.

They are peaceful but need to be kept in social groups of five or more to thrive. In a group, they form a complex hierarchy and are significantly more active and confident. Ideal tank mates include peaceful, mid-to-top dwelling species like danios, rasboras, and peaceful barbs that will not compete for bottom-level territory. Avoid housing them with aggressive cichlids or boisterous bottom-dwellers. Captive breeding is extremely rare and typically only achieved on a commercial scale using hormonal induction, making it an unrealistic goal for the average hobbyist.

Acanthopsis choirorhynchus (Bloch & Schneider, 1801) is a benthic freshwater species within the Cobitidae family of the order Cypriniformes. Its taxonomy has seen some revision, and identification can be confounded with other similar, elongated species within the genus.

Morphology: The species displays a pronounced anguilliform body shape, adapted for its fossorial existence. The head is distinguished by an elongated, conical rostrum, a key diagnostic feature. The inferior mouth is surrounded by multiple pairs of chemosensory barbels used to locate food within benthic substrates. A notable defensive characteristic, typical of the Cobitinae subfamily, is the presence of a sharp, bifid, erectile suborbital spine housed in a groove beneath each eye, which can be locked into an outward position when the fish feels threatened. The body's integument presents a cryptic pattern of brown and beige mottling, providing effective camouflage against sandy or detritus-laden riverbeds.

Distribution and Ecology: Native to Southeast Asia, A. choirorhynchus is widely distributed throughout the river systems of Thailand, Peninsular Malaysia, and the Greater Sunda Islands of Sumatra, Borneo, and Java. Its natural biotope consists of slow-moving, lotic environments such as forest streams, tributaries, and floodplain zones. These habitats are characterized by fine, unconsolidated substrates of sand, silt, or mud, which are essential for its burrowing behavior. As a benthic omnivore, its natural diet comprises small crustaceans, insect larvae, and other meiofauna that it excavates from the substrate. Its constant bioturbation plays a role in aerating the upper layers of the riverbed.

Aquarium Husbandry and Physiology: The species' adaptability to a broad range of water parameters (pH 6.0-8.0, hardness 36-215 ppm) reflects its natural occurrence in diverse aquatic environments, from acidic blackwater peat swamps to neutral, mineral-rich rivers. While tolerant, stable conditions are paramount. Its metabolism and waste production are moderate, but its fossorial habits necessitate a robust filtration system coupled with a maintenance routine that prevents the buildup of anaerobic conditions within the deep substrate. Like many loaches, A. choirorhynchus may possess the ability to perform accessory intestinal respiration, gulping atmospheric air in hypoxic conditions, though an aquarium environment should always be well-oxygenated.

Reproduction: Spontaneous captive reproduction is virtually undocumented. In its natural habitat, A. choirorhynchus is believed to be a migratory spawner. Reproductive behavior is likely triggered by significant environmental cues associated with the onset of the wet season, such as changes in water temperature, depth, flow rate, and chemistry. The inability to replicate these complex triggers is the primary barrier to successful non-hormonal captive breeding. The IUCN currently lists the species as Least Concern (LC) due to its wide distribution, although it faces localized threats from habitat degradation and pollution.