Taxonomy & naming
L107 is a code from the L-number system, which the German magazine DATZ started in 1988 to label imported loricariids that could not yet be identified. It is a trade code, not a scientific name; an undescribed form has no describing authority and no type specimens. The Südamerikafans L-Wels registry files the fish as Ancistrus sp. "L 107", and PlanetCatfish lists it as Ancistrus sp. (L107). PlanetCatfish also treats L184 as the same fish, so the form circulates as L107/L184. Hobby names are the German Brillant-Antennenwels (brilliant bristlenose) and, in English, Brilliant bristlenose pleco. The registry's bibliography runs to the Welsatlas 2 and Miniatlas L-Welse (both 2005), Wolfgang Kochsiek's article on the Brillant-Antennenwels L 107/184, and an Amazonas press-review entry from May/June 2013.
Morphology
The registry gives about 7 in total length for L107 but no written description of the fish. Brillant-Antennenwels is a label, not a diagnosis, and the characters that set L107 apart are not recorded. As an Ancistrus it is a bristlenose, one of the suckermouth armoured catfishes, with a body covered in bony plates and, in males, head tentacles (see Mating). The registry lists four similar fishes: Ancistrus sp. "LDA 3", Ancistrus dolichopterus (L183), Ancistrus sp. "L 327" and Ancistrus sp. "Breitkopf". How L107 is told apart from them is not on record.
Habitat
The registry locates L107 in the Rio Demini, part of the middle Rio Negro drainage in Amazonas state, Brazil, and classes the water type as clearwater. Substrate, flow and other habitat details are not on record for this code. Loricariids of this kind are generally associated with well-oxygenated water and with rock, wood or root cover to shelter in, but that is genus-level background, not an observation of L107.
Feeding
The registry classes L107 as predominantly herbivorous and notes that it eats aquarium plants. In the aquarium that points to a diet built on vegetable matter, sinking algae and vegetable-based foods together with fresh vegetables, and live plants may be eaten. No stomach-content studies or field feeding observations are on record for this code.
Mating
The registry's sexing note is given at genus level: in Ancistrus the males develop more and larger tentacles on the head than females. These tentacles are the "bristles" that give bristlenose catfishes their name. Ancistrus are typically cave spawners in which the male guards the eggs and larvae in the cave, and the registry rates the cave requirement as standard for the genus. No courtship or spawning behaviour has been described for L107 itself beyond the captive breeding noted below.
Breeding
The registry records L107 as bred repeatedly in aquaria and adds that a low pH of 4–4.5 is advantageous. That figure is breeding advice from the registry, not a field measurement, and it lies below the registry's general keeping range of pH 5.5–7.5. Clutch size, spawning site and fry development are not on record.
In the aquarium
The registry's keeping range for L107 is 77–84 °F and pH 5.5–7.5, aquarium guidance rather than a field measurement, and it recommends a tank about 39.5 in long. Small groups are recommended, though a single fish is possible. As with other bristlenose catfishes, clean, well-oxygenated water, caves of rock or wood and some current suit it, and territorial behaviour toward other plecos is common. The registry notes that it eats aquarium plants, which is relevant to a planted tank; soft-leaved species in particular may be nibbled.
Conservation
L107 has not been assessed by the IUCN Red List; an undescribed form cannot be evaluated until it has a name, so its status is Not Evaluated. On export, the registry notes that it is not on Brazil's 2012 positive list (the list of species cleared for ornamental export) and not on Brazil's 2020 negative list. Population size and trend are not on record. In general, collection for the trade and river engineering affect some L-number habitats.