The Rio Paraguay Bristlenose, scientifically known as Ancistrus sp. “Rio Paraguay” (L528), is an attractive and manageable bristlenose pleco originating from the Paraguay–Paraná basin in South America.

Adult Rio Paraguay Bristlenose Plecos typically reach about 4 to 5 inches (10 to 13 cm) in length. Males develop characteristic “bushy” snout tentacles and tend to be slightly larger and more robust than females. Their base coloration is a rich reddish-brown overlaid with a fine, dark honeycomb or reticulated pattern that becomes more striking with maturity.

A tank of at least 30 gallons is recommended for a single adult or a small group. The aquarium should include soft sand or fine gravel substrate, plenty of driftwood and smooth rocks for grazing surfaces, and several caves or tubes for shelter and breeding. Moderate water flow and good oxygenation support their health and natural behavior.

Water parameters should include a temperature range of 72 to 82 °F (22 to 28 °C), a pH between 6.0 and 7.5, and soft to moderately hard water. Consistent cleanliness and low nitrate levels are key to long-term well-being.

Feeding Ancistrus sp. “Rio Paraguay” is straightforward. While they graze on algae and biofilm, their diet should be supplemented with sinking algae wafers, spirulina tablets, blanched vegetables (such as zucchini, cucumber, or spinach), and occasional protein-rich treats like frozen bloodworms or brine shrimp.

Rio Paraguay Bristlenose Plecos are peaceful and suitable for community aquariums with non-aggressive mid- to bottom-dwellers. Avoid pairing them with large, overly active, or bottom-competing species.

Breeding in the aquarium is possible. The male typically selects and guards a cave, and the female deposits eggs within it. After spawning, the male tends the eggs and fry for several days. Once the fry become free-swimming, they can be raised on fine micro-foods and small algae wafers.

Ancistrus sp. “Rio Paraguay” (L528) is a striking and practical pleco variant, appreciated for its moderate size, decorative patterning, and excellent algae-grazing behavior in well-structured South American style aquariums.