Nematodes in Trichomycterus nigromaculatus (Pisces: Trichomycteridae) from the Río Gaira, Sierra Nevada de Santa Marta, Colombia

Objective. To determine the prevalence of helminth infection in Trichomycterus nigromaculatus captured in the Gaira River, in Minca, Sierra Nevada de Santa Marta, Colombia, and characterization of the physicochemistry of the aquatic environments where it occurs. Material and Methods. During both the wet and dry seasons, we collected 476 specimens of T. nigromaculatus which were dissected to examine the visceral cavity for the presence of parasites. Isolated parasites were fixed in 10% formalin for subsequent clarification. The specimens were identified by observation of adult stages under a stereoscopic microscope after clarification. Results. Only the unidentified nematode worm, Spirocamallanus sp. was found. The parasite load ranged from 0% in August to 28.57% in April with an abundance of 1.09 worms/host. Environmental parameters such as dissolved oxygen (mean:5.65 mg L-1, max:7.5 mg L-1, min:4.41 mg L-1); pH (mean:7.2, max: 9.3, min: 5.7) and conductivity (mean:72.82 μs.cm-1, max: 123.7 μs.cm-1, min: 40 μs.cm-1) had statistically significant differences in this eutrophic river environment. Conclusions. The discovery of Spirocamallanus sp. in T. nigromaculatus from the Gaira River is a new record of this parasite for the Colombian Caribbean and an extension of its geographic distribution.