Pseudacanthicus sp. L-520

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Pseudacanthicus sp. L-520, also known as the Alenquer Cactus, is a highly sought-after Brazilian loricariid among keepers of large plecos. Listed under the L-520 code, this fish is still sold under a provisional scientific designation because its species-level identification has not been established. Its sturdy body, broad head, and bony plates give it the classic appearance of a cactus pleco. This form is very rare in the aquarium trade. The specimen presented here is wild-collected and available exclusively from Ton.Fish in Canada, making it an uncommon opportunity for experienced specialists.

General species description

Pseudacanthicus sp. L-520 belongs to the group of large armored loricariids commonly called cactus plecos. The L-520 code identifies a geographic or commercial form still kept under its genus name, without a species epithet. It is a bottom-dwelling fish, most active at dusk and during the night. Its aquarium requires generous space, strong filtration, and highly oxygenated water. Despite its imposing appearance, it is not a specialized predator; it mainly defends a shelter or bottom territory. Its rarity, adult size, and wild origin make it best suited to experienced aquarists who can provide stable, long-term conditions.

Geographical origin and biotope

This form is associated with the Alenquer area in Pará State, Brazil, within the lower Amazon system. It inhabits bottom areas containing rocks, boulders, submerged wood, and shelters where it can hold position with its sucker mouth. Local flow may be strong, especially around rocky structures and channels. Warm, clean, oxygen-rich water is preferable to a stagnant aquarium. The layout should include solid shelters and shaded areas, together with continuous water movement. Amazonian riverbank vegetation influences the surrounding habitat, although the fish mainly occupies the lower part of the watercourse.

Precise location and local name

The commercial name Alenquer Cactus refers to Alenquer, a municipality in Pará located on the northern bank of the lower Amazon. The L-520 code is the main identifier used by aquarists and importers for this form. In the specialist trade, the names Pseudacanthicus sp. L-520 and Alenquer Cactus are the most useful aquarium references; no separate Brazilian vernacular name is required for its aquarium identification. This geographic reference matters because L-numbers preserve the presumed origin of loricariids before a possible scientific description. L-520 should therefore not automatically be replaced by the name of an already described species.

Appearance and physical characteristics

Pseudacanthicus sp. L-520 has a stocky body, a broad head, and heavy armor formed by bony plates. As in other Pseudacanthicus, the cheeks and fins carry odontodes that make handling potentially difficult. The base coloration is generally dark, with lighter markings emphasizing the body and fin structure. Its ventral mouth is used to attach to surfaces and collect food. Its appearance as a robust cactus pleco sets it apart from more slender loricariids. A container is preferable to a fine mesh net during handling, since the spines and odontodes can become caught.

General diet

Its diet should be varied and based mainly on plant matter and sinking foods. Offer loricariid wafers, algae-based foods, and blanched vegetables such as zucchini or cucumber on a regular basis. Food should reach the bottom after the lights are partially dimmed, since the species is most active in the evening. An occasional more protein-rich food can supplement the diet, but it should not dominate the menu. Natural wood can enrich the layout and support grazing behavior. A generous yet controlled feeding routine helps maintain a healthy fish while limiting excess organic waste.

Essential data

• River of origin: lower Amazon system, Alenquer area
• Local name used: Alenquer Cactus
• Origin of the scientific name: Pseudacanthicus is a genus name; sp. indicates an unspecified species and L-520 is an aquarium trade code
• Etymology of the complete name: Pseudo means false or resembling; Acanthicus refers to a genus of spiny loricariids; sp. means species; L-520 is a commercial classification number
• Common/vernacular names: Alenquer Cactus, cactus pleco
• Family: Loricariidae
• Subfamily: Hypostominae
• Name pronunciation: soo-doh-ak-an-ti-kus - ess pah five hundred twenty
• Maximum adult size: about 30 cm
• Water temperature and pH: 25 to 30 °C; pH around 6.0 to 7.5
• Watercourse appearance and surrounding vegetation: warm, oxygen-rich water, rocky structures, submerged wood, and Amazonian riverbank vegetation
• Typical tankmates: Acarichthys heckelii, Geophagus proximus, Pterophyllum scalare, Hemigrammus rhodostomus
• Temperament and behavior: generally discreet, bottom-dwelling, and territorial around shelters
• Water depth: bottom areas and shelters within the watercourse
• Sexual dimorphism: difficult to determine with confidence in juveniles; adults may differ in body width and odontode development
• Bottom structure and flow: rocky or gravelly substrate, submerged wood, moderate to strong current, and high oxygenation
• Presented status: wild-collected, very rare, and exclusive to Ton.Fish in Canada

In your aquarium

To succeed with Pseudacanthicus sp. L-520, provide a large aquarium, a stable layout, and several shelters suited to its adult size. Oversized filtration, regular water changes, and strong oxygenation are essential for a wild specimen. Feed it after the lighting is reduced and monitor competition for bottom space. Avoid repeated handling because of its odontodes. Since this is a very rare, wild-collected fish, every acquisition deserves careful acclimation and consistent maintenance. Respecting its needs for space, current, and shelter remains the foundation of successful long-term care.