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First record of Trichodina centrostrigeata Basson, Van As & Paperna, 1983 (Ciliophora: Trichodinidae) from Oreochromis niloticus (Linnaeus, 1758) cultured in southeastern Mexico.

Ciliated protozoa of the genus Trichodina are one of the most common ectoparasites of both freshwater and marine fishes. These parasites are capable in some cases of inflicting significant damage to their hosts with resultant mortalities. Despite the threat they pose in other regions of the world, in Mexico, there are few studies (Rodriguez-Santiago, 2002). The study of parasites as pathogenic agents for host fish is important in the ingrowth processes, in particular in aquaculture conditions. Infestation in fish increases when they are cultured intensively since high density causes an increase in the parasite populations, which may cause an epizootic mainly in the case of parasites of a direct cycle such as certain protozoans (Woo, 1999). Trichodinids, known for their frequency and negative effects, have been found as parasites especially in weakfish in overpopulated conditions in supply pools with low oxygen environments (Snieszko & Axelrod, 1971). Cichlids and carps are commonly affected by trichodinids which cause "epizootic" buds with great economic losses in cultures (Paperna, 1996). The larval stages of fish are the most sensitive to the development of protozoan diseases, including trichodiniasis. Clinical signs of trichondiniasis consist of an increase of the quantity of white mucus, fin raveling, lethargy, anorexia, scale loss and tendency to group near the water entrances. The fish present skin hyperemia and when the gills are involved it may cause asphyxia. The problem is more complicated when there are secondary infections, bringing as a consequence bacteria diseases, together constituting a set of considerable processes in the fish pathology. Trichodina centrostrigeata Basson, Van As & Paperna, 1983 (Basson et al., 1983), among other ciliated parasites, are natives from Asia or Africa but have been disseminated to many localities worldwide (Rodriguez-Santiago, 2002). Understanding Oreochromis niloticus in cultured freshwater fish is central to the aquaculture industry in Mexico, which ranks 28th in the world with a production of 143,747 t of freshwater species (FAO, 2005, 2012, 2013).

In this study, we report a new geographic location in the southeastern region of Mexico for T. centrostrigeata parasitizing the skin, fins, and gills of O. niloticus, previously identified for T. niloticus from southern Africa (Basson et al., 1983). Nile tilapia is cultured at high densities in fish farms in southeastern Mexico, Villahermosa (Tabasco). Fish showed characteristic disease signs: rubbing on the sides or bottom on the pond, caudal fin erosion, hemorrhagic areas in the skin (Valladao et al., 2013, 2014, 2015, 2016), abundant slime and corneal opacity (29%). Smears of trichodinids were taken from the skin and gills of 240 infested O. niloticus fingerlings and juveniles. The silvery stain by Klein (1958) was used for detailed observation of the denticle structures, the fixation disk characteristics and the number of their constituents, and the Harris' hematoxylin solution was used for the observation of the nuclear apparatus as additional information. The methodology reported by Lom (1958) and Wellborn (1967) was used for taxonomic identification. Once the tinted slides were mounted through the technique by Klein (1958), they were observed in detail under the optical microscope (Motic BA310E) searching for trichodinids (Fig. 1). Those that were completely mature and well-shaped with all the constituents of the adhesive disk clear and well tinted were selected. At a 1000x amplification, the denticle morphology of each one of the organisms was carefully observed: blade and ray, the degree of silvery impregnation of the center of the adhesive disk and presence or absence of chitin structures, etc. The angle described by the adoral spiral was also observed. All of these characteristics were compared to the descriptions by Lom & Dykova (1992) to locate them taxonomically in a tentative way, and this was followed by the review of the original studies for the determination of the species, for which the corresponding measurements were also done. The specific differentiation was based on a description for trichodinids as ectoparasites of cichlids and cyprinid fishes in South Africa and Israel (Basson et al., 1983). Trichodinids were counted using an optical microscope (Motic BA310E) at 60x and 100x magnification (Rodriguez-Santiago, 2002). Although T. centrostigeata was documented in T. nilotica in northwestern Mexico by Rodriguez-Santiago (2002), this information was never formally published. The ectoparasite species found was identified as Trichodina centrostrigeata, which constitutes the first record for Mexico. The morphologic characteristics that led to its identification were: wide triangular denticle blades with blunt edges, a straight thorn rod-like shape and a curving slightly backward about the blade (Fig. 1). The morphometric charac-teristics of T. centrostrigeata are shown in Table 1. The taxonomical characteristics considered were: wide triangular denticle blades with blunt edges, a straight thorn rod-like shape and a curving slightly backward about the blade.


Thanks for the support during the elaboration process of this work to Lety Sanchez. We also thank Dr. Rafael Martinez Garcia, M.C. Serapio Lopez Jimenez, M.C. Alejandro McDonald Vera and M.C. Miguel Angel Perez Mendez for the time dedicated to the review of this work and for comments. In the same way, we thank Guadalupe Garcia Jimenez, Luisa Ramos Colorado and Guadalupe Reyes for their support in the laboratory analysis, and to the Tropical Aquaculture Laboratory of the division for their support in the collections of the organisms (UJAT). We are grateful to Karen Englander (Faculty of Languages, University of Baja California) for her English review and editing of the manuscript. Special thanks to the anonymous reviewers for their comments to improve this article.


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Maria Amparo Rodriguez-Santiago (1,2), Leticia Garcia-Magana (3), Mayra I. Grano-Maldonado (4) Enrique N. Silva-Martinez (5), Jesus Guerra-Santos (5) & Rolando Gelabert (5)

(1) Consejo Nacional de Ciencia y Tecnologia (CONACyT), Mexico

(2) Facultad de Ciencias Naturales, Centro de Investigacion de Ciencias Ambientales Universidad Autonoma del Carmen, Campeche, Mexico

(3) Division Academica de Ciencias Biologicas Villahermosa Universidad Juarez Autonoma de Tabasco, Tabasco, Mexico

(4) Universidad Autonoma de Occidente, Mazatlan, Sinaloa, Mexico

(5) Facultad de Ciencias Naturales, Centro de Investigaciones en Ciencias Ambientales Universidad Autonoma del Carmen, Ciudad del Carmen, Campeche, Mexico

Corresponding author: Maria Amparo Rodriguez-Santiago (

Corresponding editor: Sandra Bravo

Received: 20 February 2018; Accepted: 25 October 2018

DOI: 10.3856/vol47-issue2-fulltext-18
Table 1. Comparative measurements ([micro]m) of Trichodina
centrostrigeata taken from Oreochromis niloticus (Basson et al.,
1983),O. mossambicus, Tilapia rendalli, Pseudocrenilabrus philander, T.
sparrmanii (Basson & Van As, 1994) and O. niloticus Egyptian variety
(Rodriguez-Santiago, 2002). Rp/d: number of radial pins per denticle,
Med: macronucleu external diameter. Numbers represent the absolute
minimum, and maximum values observed. The average [+ or -] SD (standard
deviation) is indicated within parenthesis. The number located after SD
indicates the quantity of trichodinid specimens that were measured.

                               Basson et al. (1983)
                              Oreochromis niloticus

Position on host                  Skin and fins
Locality                           South Africa
Body diameter           31.2-45.8 (37.6 [+ or -] 3.6, 100)
Adhesive disc diameter  18.7-33.3 (23.2 [+ or -] 2.5, 100)
Central rods            12-16 (14, 100)
Number of denticles     26-30 (28, 100)
Rp/d                     6-7 (7, 100)
Denticle lengh           2.0-6.2 (4.1 [+ or -] 0.6, 100)
Blade lengh              2.8-6.4 (5.2 [+ or -] 0.7, 100)
Ray lengh                1.13.0 (1.9 [+ or -] 0.3, 100)
Lightning length         3.2-6.0 (4.5 [+ or -] 0.6, 100)
Med                     20.9-49.7 (37.6 [+ or -] 6.9, 23)

                             Basson & Van As (1994)
                              Cichlids and cyprinid

Position on host                  Skin and fins
Locality                    South Africa, Philippines
Body diameter           30.0-45.0 (36.0 [+ or -] 4.2, 16)
Adhesive disc diameter  18.5-26.0 (21.7 [+ or -] 2.4, 16)
Central rods            13-16 (14, 12)
Number of denticles     24-29 (26, 16)
Rp/d                     7-8 (8, 7)
Denticle lengh           3.0-5.0 (4.3 [+ or -] 0.6, 13)
Blade lengh              5.0-6.0 (5.5 [+ or -] 0.5, 15)
Ray lengh                1.0-1.5 (1.1 [+ or -] 0.2, 15)
Lightning length         3.5-5.0 (4.3 [+ or -] 0.6, 15)
Med                                  --

                            Rodriguez-Santiago (2002)
                              Oreochromis niloticus
                                Egyptian variety

Position on host                  Skin and fins
Locality                         Sinaloa, Mexico
Body diameter           30-44 (37.51 [+ or -] 3.9, 31)
Adhesive disc diameter  18-38 (19.64 [+ or -] 2.1, 31)
Central rods            12-15 (13, 31)
Number of denticles     23-29 (26, 31)
Rp/d                     6-8 (6, 31)
Denticle lengh           3.3-5.6 (4.29 [+ or -] 0.74, 31)
Blade lengh              3.3-6.7 (4.55 [+ or -] 0.77, 31)
Ray lengh                2.22-6.7 (2.73 [+ or -] 0.89, 31)
Lightning length         3.3-7.8 (5.29 [+ or -] 0.97, 31)
Med                     19-37 (32 [+ or -] 7.4, 7, 13)

                                   This study
                             Oreochromis niloticus

Position on host                 Skin and fins
Locality                      Villahermosa, Mexico
Body diameter           30-43 (36.0 [+ or -] 4.2, 25)
Adhesive disc diameter  18-25.0 (21.7 [+ or -] 2.4, 25)
Central rods            12-16 (13, 25)
Number of denticles     20-29 (26, 25)
Rp/d                     7-8 (7, 25)
Denticle lengh           3-5.5 (4.1 [+ or -] 0.6, 25)
Blade lengh              5.0-6.5 (5.5 [+ or -] 0.5, 25)
Ray lengh                1.0-1.5 (1.1 [+ or -] 0.3, 25)
Lightning length         3-5.0 (4 [+ or -] 0.6, 20, 25)
Med                                     --
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Title Annotation:Short Communication
Author:Rodriguez-Santiago, Maria Amparo; Garcia-Magana, Leticia; Grano-Maldonado, Mayra I.; Silva-Martinez,
Publication:Latin American Journal of Aquatic Research
Date:May 1, 2019
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