The L191 Royal Pleco, scientifically known as Panaque sp. L191, is a large, wood-eating freshwater catfish native to the slow-moving, tannin-rich rivers of Colombia, particularly within the Río Caquetá and upper Amazon Basin. Known for its impressive size, armored body, and reliance on driftwood in its diet, this pleco is highly sought after by aquarists with large, well-maintained aquariums.

Physically, Panaque sp. L191 has a broad, flattened body with a distinctive bony headplate and a powerful sucker mouth adapted for rasping wood and biofilm. Its coloration is typically dark olive green to brown, with lighter streaks running across its body and fins. Unlike many other plecos, it has red or orange eyes, a characteristic trait of the Panaque genus. Juveniles display more pronounced patterns, which may fade slightly as they mature. Adults can reach sizes of 12 to 14 inches (30 to 35 centimeters), requiring a spacious aquarium setup.

In the aquarium, L191 Royal Plecos require a large tank of at least 100 gallons, with driftwood being an essential part of their habitat. They depend on wood both for shelter and as a primary food source, as their specialized teeth are adapted for digesting lignin and cellulose. The tank should include soft sand or fine gravel substrate, plenty of hiding spots created by large driftwood pieces, and subdued lighting to mimic their natural environment. They thrive in moderate water flow, so strong filtration is necessary to handle their heavy bioload.

Water parameters should closely match their natural habitat, with a temperature range of 77 to 84°F (25 to 29°C), a pH between 6.0 and 7.5, and soft to moderately hard water. Frequent water changes are required to prevent waste buildup, as they produce a large amount of detritus due to their high-fiber diet.

Feeding Panaque sp. L191 requires an understanding of their unique dietary needs. Unlike most plecos, they primarily consume wood, which aids in digestion and provides essential nutrients. In addition to driftwood, they should be fed high-fiber foods such as sinking algae wafers, fresh vegetables like zucchini, cucumber, and sweet potato, as well as occasional protein sources like shrimp or bloodworms. However, excessive protein should be avoided, as their digestive system is better suited for plant-based foods.

L191 Royal Plecos are generally peaceful but can be territorial toward other bottom-dwelling fish, especially other large plecos. They are best kept with medium to large, peaceful tank mates such as larger tetras, silver dollars, geophagus cichlids, or other South American species. Avoid aggressive or overly active fish that may disturb their feeding and resting habits.

Breeding Panaque sp. L191 in captivity is extremely rare and not well-documented. In the wild, they are believed to be cave spawners, laying eggs inside submerged logs or rocky crevices. Due to their size and specific environmental needs, successful breeding in home aquariums is highly unlikely.

Overall, Panaque sp. L191 (L191 Royal Pleco) is a unique and fascinating species that requires specialized care, particularly regarding its dietary needs and tank setup. Its impressive size, wood-eating behavior, and peaceful nature make it an excellent choice for experienced aquarists with large, well-maintained aquariums.