Taxonomy & naming
Parodon alfonsoi was described in 2011 by Londoño-Burbano, Román-Valencia and Taphorn. The species epithet alfonsoi honours Alfonso Londoño Orozco, the father of the description's first author — a dedication rather than a description of the fish itself. It belongs to the genus Parodon, one of several genera in the family Parodontidae (the scrapetooths), a Neotropical group endemic to river systems from Panama south to the Paraná basin. The Catalog of Fishes (Eschmeyer, California Academy of Sciences) is the governing authority for the valid name and combination used here; nothing in the cached sources suggests the species has been moved to another genus since its description.
Parodontidae sits within Characiformes but well outside the piranha-pacu family Serrasalmidae covered elsewhere in this "Piranhas & Pacus" section — Parodon and its relatives are unrelated in diet and body plan to the true piranhas and are grouped here only as one of the non-tetra characin lineages of South America. The genus is characterised by a distinctive, downturned mouth and a specialised, rotating tooth-replacement system built for scraping rather than biting.
Morphology
Parodon alfonsoi is a small fish: FishBase records a maximum size of 4 in standard length, with the holotype specimen (CIUA 1125) measuring 4 in SL. Like other Parodon species it has an elongated, subcylindrical body suited to holding position in current, and an underslung, scraper-adapted mouth rather than the terminal, tooth-lined jaw of a predatory characin. FishBase classes the species' trophic level at 2.5 (± 0.1 standard error), consistent with a herbivore-to-omnivore grazer rather than anything higher on the food chain, and notes it as harmless to humans.
Detailed colouration and fin-ray counts specific to P. alfonsoi were not available in the cached sources beyond the holotype description; readers wanting full meristic data should consult the original 2011 description. What is well documented at the family level is the elaborate, continuously replaced row of scraping teeth shared by Parodon species, adapted for rasping algae and biofilm from rock surfaces in fast water.
Habitat
The species is known only from the río Tucuy, a tributary of the río Calenturitas in the lower Magdalena River basin of Colombia — its type locality and, as far as the cached sources indicate, its entire known range, making it a single-river Colombian endemic. FishBase lists its habitat as pelagic-freshwater within that system, and family-level accounts describe Parodon species generally as rheophilic specialists, meaning they depend on flowing, well-oxygenated water over rocky or gravel substrate rather than still or slow backwaters.
No specific temperature or pH range for P. alfonsoi was found in the cached sources. Given the family's rheophilic habit and its lowland Magdalena-basin locality, water is presumed warm and well-oxygenated, but that inference should not be mistaken for a measured range — data on this point is genuinely sparse and any numbers offered would not be traceable to a real source.
Feeding
Parodon alfonsoi is a specialised algae and biofilm scraper. FishBase's trophic-level estimate of 2.5 places it at the herbivore-omnivore transition, consistent with the family-wide Parodontidae strategy of rasping algae, diatoms and biofilm from rock surfaces with a purpose-built, downturned mouth and a continuously replacing row of scraping teeth. This is a fundamentally different feeding mode from the predatory or fruit-and-seed-eating characins covered elsewhere in this section — there is nothing in the record to suggest P. alfonsoi takes live prey or behaves as anything but a grazer.
No aquarium feeding observations for this species were found in the cached sources; the diet description above rests on the trophic-level data and the well-documented feeding ecology of Parodon as a genus.
Mating
No courtship or spawning behaviour has been documented for Parodon alfonsoi in the cached sources. The species is not established in the aquarium hobby, and nothing resembling a description of pairing, colour change, or breeding condition was found. This should be stated plainly rather than inferred from other characins.
Breeding
Breeding biology for Parodon alfonsoi is undocumented in the available sources — there is no record of the species being spawned in aquaria, and the cached research notes explicitly flag its breeding as "data sparse; not confirmed in aquaria." It should not be assumed to follow the open-water egg-scattering pattern sometimes seen in other small Neotropical characins; with no direct evidence for this species, the honest position is that its reproductive behaviour in the wild and in captivity is simply unknown.
In the aquarium
Parodon alfonsoi is not an established aquarium fish; the cached research notes describe it as rare in the trade with data sparse on captive care, which likely reflects both its restricted single-river distribution and its Endangered status rather than any unsuitability as an aquarium species. At barely 4 in it would be a modestly sized fish by the standards of this section, and the wider Parodontidae are generally described as peaceful, non-predatory algae grazers that can be kept solitary or in groups — a world away from the piranhas, pacus and predatory characins that dominate the "Piranhas & Pacus" family.
Any prospective keeper should start from the premise that this is a rheophilic species: family-level accounts describe Parodon as fast-water specialists that do best with strong current and well-oxygenated water over hard substrate, more akin to a hillstream or riffle setup than a still community tank. Given the species' Endangered status and single-locality endemism, any specimens reaching the hobby should raise real questions about the sustainability and legality of their collection.
Conservation
The IUCN Red List assesses Parodon alfonsoi as Endangered, with the assessment dated 2014. FishBase records the basis as criterion B1ab(iii), which reflects a very small area of occupancy in a single river system alongside evidence or inference of ongoing habitat decline — consistent with the species' known range being restricted to the río Tucuy tributary of the río Calenturitas in the lower Magdalena basin.
Because the entire known population sits in one small stream system in a heavily developed part of Colombia, the species carries the classic risk profile of a narrow-range freshwater endemic: any local habitat degradation, water diversion or pollution event in that single tributary could affect a meaningful share of the total population. No information on a targeted conservation programme for this species was found in the cached sources; its listing rests on range and habitat criteria rather than direct population counts.