Hoplisoma loxozonum

Originating from Colombia, the Loxozonus Corydora is a small-sized, schooling catfish that actively forages at the bottom of freshwater aquariums. These peaceful bottom-dwellers are a great addition to community tanks with other small, non-aggressive species. Because they are social by nature, they must be kept in groups to feel secure and exhibit their natural, active behaviors. In the aquarium, they will spend their time sifting through the substrate in search of food.

A varied omnivorous diet is essential for their health, and they readily accept high-quality sinking pellets, wafers, and various frozen or live foods. These fish are relatively hardy but thrive in stable, clean water with a gentle current. They prefer cooler tropical temperatures and are sensitive to poor water conditions, so regular maintenance is important. A fascinating characteristic of this species is its ability to occasionally swim to the surface to take a gulp of air, which is a natural adaptation and perfectly normal behavior. Their manageable size and peaceful disposition make them a popular choice for aquarists.

The Loxozonus Corydora is a benthic catfish native to the slow-moving rivers and tributaries of Colombia. In its natural habitat, it inhabits soft, sandy riverbeds often covered in leaf litter and biofilm. These environments typically have slightly acidic to neutral water with low mineral content and a gentle current. Replicating these conditions in an aquarium is key to their long-term health. A tank with a soft substrate, like sand or fine, rounded gravel, is crucial to protect their sensitive barbels, which they use to forage for food. They are known to uproot delicate plants while sifting for edibles, so robust, well-rooted plants or epiphytes are recommended.

As a highly social species, they must be housed in a school. Keeping a group encourages natural foraging and shoaling behaviors while reducing stress, making them more confident and active. Lone individuals will be shy, stressed, and prone to illness. They are moderately active, displaying periods of rest followed by bursts of foraging and exploration across the tank bottom. Despite their small size, they are fast swimmers and add a dynamic element to the lower level of an aquarium.

Their omnivorous diet in the wild consists of small crustaceans, insects, worms, and plant matter. In captivity, this should be replicated with a varied diet of high-quality sinking pellets or wafers as a staple. This diet should be supplemented regularly with frozen or live foods to ensure proper nutrition. They are best fed once daily, as their low metabolism and efficient digestion mean they produce relatively little waste for their size, contributing a manageable bioload to the aquarium ecosystem. A unique physiological trait is their ability to utilize atmospheric oxygen through intestinal breathing. They will occasionally dart to the surface for a gulp of air, a fascinating adaptation for surviving in low-oxygen environments. While this is normal, frequent air-gulping could indicate poor water quality or inadequate aeration.

Hoplisoma loxozonum is a species of freshwater catfish belonging to the family Callichthyidae within the order Siluriformes. This species, like many of its congeners, was historically classified under the extensive genus Corydoras but has been re-assigned to Hoplisoma following recent taxonomic revisions that aimed to create more monophyletic groupings. Native to river systems in Colombia, it occupies a specific ecological niche as a benthic micro-predator and detritivore.

The morphology of H. loxozonum is characterized by a fusiform body shape, slightly flattened ventrally, which is well-suited for its bottom-dwelling lifestyle. Like other members of Callichthyidae, its body is protected by a double row of overlapping bony plates or scutes rather than scales. Surrounding its inferior mouth are sensitive barbels equipped with chemosensory receptors, which are instrumental in locating food within the substrate. Its environmental interactions include rooting through the substrate, which can contribute to bioturbation, and consuming biofilm that grows on surfaces. Physiologically, this species is noted for its adaptation to potentially hypoxic conditions through accessory intestinal respiration, allowing it to supplement gill respiration with gulps of atmospheric air. Its metabolism, oxygen consumption, and subsequent waste production are all low, reflecting an energy-efficient life strategy common among benthic foragers. The International Union for Conservation of Nature (IUCN) has not yet evaluated the conservation status of this species, so it is currently listed as Not Evaluated (NE).

Breeding the Loxozonus Corydora is considered a moderately difficult endeavor, achievable for the dedicated hobbyist who can replicate specific environmental triggers. Success begins with a well-conditioned group of adults. For optimal results, a breeding group should be established with a higher ratio of males to females, such as two or three males for every female, to encourage spawning activity. Differentiating the sexes can be done by observing their body shape; mature females are typically larger, plumper, and have a broader, more rounded body profile when viewed from above, whereas males are noticeably smaller and more slender.

To induce spawning, the aquarist should first condition the fish for several weeks with a nutrient-rich diet of live and frozen foods. The primary trigger for spawning is a significant water change with water that is cooler than the current tank temperature. This simulates the onset of the rainy season in their natural environment. Increasing aeration and water flow during this period can further encourage the process. When ready to spawn, the fish will become highly active. The pair will engage in a courtship behavior that culminates in the male and female forming a "T-position," where the female takes the male's sperm into her mouth to fertilize her eggs. The female will then release and deposit her adhesive eggs, which she carries in a pouch formed by her pelvic fins, onto cleaned surfaces like the aquarium glass, filter tubes, or broad plant leaves. This process is repeated until she has deposited all of her eggs.

Once spawning is complete, it is crucial to remove the adult fish from the breeding tank, as they will consume their own eggs. The eggs can be left in the breeding tank or moved to a separate, well-aerated container. After a few days, the eggs will hatch, and the fry will initially survive by consuming their yolk sacs. Once the yolk sacs are absorbed, the fry must be fed microscopic foods such as infusoria, microworms, or liquid fry food. As they grow, their diet can be transitioned to newly hatched brine shrimp and finely crushed flake or pellet food.