Vertebrae: 22 - 23. Presence of an iris diverticulum;
elevated, enlarged odontodes at posterior supraoccipital
tip; lateral series 24-25; lateral line canals only
on first 4-6 anterior plates in median series; lateral
trunk coloration variable, including either row of
4-6 distinct dark blotches or distinct dark stripe
extending from pterotic posterior process to base
of caudal fin, or diffuse mixture of those two colour
patterns; premaxillary teeth 14-18 (commonly 15-16);
mandibular teeth 12-16 (commonly 14); caudal vertebrae
15-17, modally 17; triangular pigment mark at anterior
dorsal- fin base occasionally faint or absent. Habitat:O. mimulus is found in streams with
dark, slightly turbid water, flowing through a landscape
of mixed low forest and pasture. Collected at the
margin of an open field, but the stream flowed through
dense low forest left along its bank and providing
shadow. Usually occurs in areas with sandy bottom,
bank vegetation entering water or with marginal aquatic
plants, dark, clear or slightly turbid water and limited
associated fauna. Mimics Corydoras diphyes.
Mimicry is unusual because the two species occupy
different microhabitats and it is hypothesized to
operate with a primarily visual predator moving between
the microhabitats, tentatively identified as the cichlid
Crenicichla lepidota.Aquarium Care:
This is a small group of Loricariids which do well
in aquariaand will keep the algae down without
harming the plants in the tank.Best to keep
in a group with more males for breeding purposes.
Reproduction: The females will lay
eggs on the plants and tank glass after the females
have been chased around the tank by the male. Like
Corydoras they present a t-position breeding
algae, tablet foods, flake and small frozen foods.
Etymology: Its specific name is derived
from a Latin word, mimulus, diminutive of minus, meaning
actor, given with reference to the mimicry in colour
pattern with Corydoras
South America:Monday River, Paraná River basin,
Paraguay. Type locality: Paraguay:
Departamento Caaguazú: Río Paraná
drainage, small stream (arroyo) at Estancia María
Belén, 8 km from Colone Patricio Colman, 25º40'13"S,
T.E. and S.O. Kullander, 2003. Corydoras diphyes
(Siluriformes: Callichthyidae) and Otocinclus mimulus
(Siluriformes: Loricariidae), two new species of catfishes
from Paraguay, a case of mimetic association. Ichthyol.
Explor. Freshwat. 14(3):249-272. Evers, H.-G. & I.Seidel: Mergus,
Baensch Catfish Atlas Volume 1, 1st English edn., 2005.
Pp.944. Ferraris, C.J. Jr.,
2007. Checklist of catfishes, recent and fossil (Osteichthyes:
Siluriformes), and catalogue of siluriform primary types.
Zootaxa 1418:1-628. Froese, R. and D. Pauly. Editors. 2018.
FishBase. World Wide Web electronic publication. www.fishbase.org,