Trichodina modesta: an exotic ciliate in the Neotropical region parasitizing an unusual host

Abstract

In this study, an important ornamental fish, Betta splendens (Osphronemidae), from three different Brazilian states was examined for parasitic infestations. Smears with parasites were impregnated with silver nitrate or stained using Giemsa for taxonomic evaluation. A disc-shaped trichodinid with a body diameter of 39.7 ± 3.3 µm, adhesive disc diameter of 32.9 ± 3.1 µm and denticulate ring diameter of 19.5 ± 2.0 µm was found. The morphological characteristics resembled those of Trichodina modesta Lom, 1970, a species that shows clear host specificity for Cypriniformes. Until now, its occurrence was restricted to the Eurasian region. In the present study, a new host for T. modesta is reported and therefore the first occurrence of this species in the Americas. The parasite was possibly introduced into the Neotropical region through the exotic fish trade, especially of Cypriniformes used by aquarists. The distribution of this ciliate is discussed and a checklist of localities and hosts for the species is provided.

Trichodiniasis in Nile tilapia hatcheries: Diagnosis, parasite:host-stage relationship and treatment

“…New reports of uncommon trichodinids in South America have increased. Recently, Valladão et al (2015b) have described parasitism by the Euro-Asiatic trichodinid Trichodina modesta Lom, 1970in cultivated Betta splendens Regan, 1910in Brazil. Several years ago, Van As and Basson (1989 described the risks of introducing trichodinids into new areas through the dispersal of cichlids worldwide.…”

Trichodinidae in commercial fish in South America

“…only in the gills of Carnegiella strigata (14.3%), Carnegiella marthae (7.9%) and Nannostomus eques (9.7%), with the highest mean intensity in C. strigata (6.5 ± 3.5 parasites/fish). Trichodina modesta, which was described only in Eurasia and as a specific parasite of Cypriniformes, was also found by Valladão et al (2015) for the first time, infecting B. splendens in Brazil. This is therefore the first report of this trichodinid in the Americas (Table 1).…”

“…(see in SINDAN 2016). Despite the small number of products that are legally available for aquaculture in Brazil, a great variety of chemical products for which the lethal and clinical concentrations, length of exposure, waiting period and environmental impact have not yet been defined are currently being used there (Valladão et al 2015). Therefore, although different studies conducted in Brazil have demonstrated that some chemotherapeutic and phytotherapeutic agents present antiparasitic effectiveness, their use has not been approved through legislation, and use of these products is limited.…”

Pathological assessment of exotic channel catfish infected by South American Anodontites trapesialis from Brazilian fish farm

“…Usually the introduction of exotic fish may offer risks of introduced pathogens in new areas, as described in the dispersion of copepods (Portz, Antonucci, Ueda, Dotta, Guidelli, Roumbedakis, Martins, Carniel & Tavechio ) and trichodinids (Van As & Basson ; Valladão, Giannecchini, Martins & Pádua ). However, in this case the opposite occurred, when the lasidium of mollusk A. trapesialis (a South American invertebrate) effectively established a parasitic relationship with an introduced North American fish.…”