Taxonomy & naming
Titanicus pleco and, in German, Titanic-Kaktuswels are the trade names for L273, a number from the series DATZ started for loricariids that could not yet be named. It carries no authority and has no type specimens. The registry lists it as Pseudacanthicus sp. "L 273", with no cf. or aff.; PlanetCatfish files it as Pseudacanthicus sp. (L273). Similar catfishes named are P. pitanga (L24), P. pirarara (L25), Pseudacanthicus sp. L65, P. cf. leopardus L114 (LDA 7) and P. leopardus. The bibliography cites the Welsatlas 2 (2005), the Miniatlas L-Welse (2005) and several Amazonas magazine items.
Morphology
The registry puts L273 at more than 15.5 in total length, with no measured maximum on record. Titanic and Titanicus are trade labels, not descriptions, and nothing is said of the colour pattern or other diagnostic characters. In form it is a typical Pseudacanthicus, a suckermouth catfish armoured in bony plates bearing small odontodes.
Habitat
L273 is recorded from the Rio Tapajós in the state of Pará, Brazil, within the Amazon system, in clearwater. The registry lists two fishes as found together with it, Pseudacanthicus sp. L275 and Scobinancistrus sp. L368. No habitat place, substrate, depth or current is on record, and the temperature and pH figures are aquarium ranges, not field measurements.
Feeding
The registry classes L273 as predominantly a carnivore that does not eat plants. In the aquarium that points to meaty sinking foods such as frozen mussel, prawn and large bloodworm, plus sinking carnivore pellets. The wild diet has not been documented for this code, so the diet class is the only guide, and a varied menu within it is the usual approach.
Mating
The registry's sexing note applies to the genus, not to L273 specifically. In Pseudacanthicus the male has a longer, broader head, is often more attractively coloured and often has a larger dorsal fin. The genus is typically a cave spawner, the male guarding the eggs and larvae in the cave, but courtship and spawning behaviour have not been described for L273.
Breeding
The registry records L273 as bred in aquaria. Its bibliography lists an article by Wai Meng Lui in Amazonas (March/April 2017) on a successful breeding of Pseudacanthicus sp. Titanic, though no clutch size, incubation time or description of the fry is given. Spawning in a cave with male care is the genus-typical pattern. The registry also lists a known hybrid with Pseudacanthicus leopardus.
In the aquarium
Keeping guidance for L273 is 79–86 °F and pH 5–7 in a tank at least 59 in long; these are aquarium figures, not field measurements. Small groups are recommended, and a single fish is possible. A large catfish needs clean, well-oxygenated water with current, rock or wood caves, and tankmates able to cope with the territorial behaviour common among plecos.
Conservation
L273 is Not Evaluated by the IUCN Red List, which cannot assess an undescribed form until it has a name. According to the registry, it is on Brazil's 2012 positive list of species cleared for ornamental export and not on the 2020 negative list. Its wild status is not known; collection for the trade and river engineering are general pressures on some L-number habitats.