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Neotropical Helminthology

Neotropical Helminthology, 2026, vol. 20 (2), 259-270

ORIGINAL ARTICLE / ARTÍCULO ORIGINAL

PARASITIC NEMATODES IN THE MAYAN CICHLID MAYAHEROS

UROPHTHALMUS SOLD IN CIUDAD DEL CARMEN, CAMPECHE:

POTENTIAL IMPLICATIONS FOR PUBLIC HEALTH

NEMATODOS PARÁSITOS EN LA MOJARRA CASTARRICA MAYAHEROS

UROPHTHALMUS COMERCIALIZADA EN CIUDAD DEL CARMEN,

CAMPECHE: POSIBLES IMPLICACIONES PARA LA SALUD PÚBLICA

Celso Rubén Canche-Tun1, María Amparo Rodríguez-Santiago2,3,4,5*, Enrique Ávila2, José Iannacone4,5,

Stephanie Córdova-Osorio1, Deysi Medrano-Domínguez1, Ianna Guzmán-Medrano6, Mario Loya-

Bautista2,7 & Juan Manuel Osuna-Cabanillas8

ISSN Versión Impresa 2218-6425 ISSN Versión Electrónica 1995-1403

DOI: https://doi.org/10.62429/rnh20262022201

Este artículo es publicado por la revista Neotropical Helminthology de la Facultad de Ciencias Naturales y Matemática, Universidad Nacional Federico

Villarreal, Lima, Perú auspiciado por la Asociación Peruana de Helmintología e Invertebrados Aﬁ nes (APHIA). Este es un artículo de acceso abierto,

distribuido bajo los términos de la licencia Creative Commons Atribución 4.0 Internacional (CC BY 4.0) [https:// creativecommons.org/licenses/by/4.0/

deed.es] que permite el uso, distribución y reproducción en cualquier medio, siempre que la obra original sea debidamente citada de su fuente original.

1 Posgrado en Restauración Ecológica, Centro de Investigación de Ciencias Ambientales, Facultad de Ciencias Naturales,

Universidad Autónoma del Carmen (UNACAR), Ciudad del Carmen, Campeche, México.

2 Instituto de Ciencias del Mar y Limnología, Estación “El Carmen”, Universidad Nacional Autónoma de México, Ciudad del

Carmen, Campeche, México.

3 Secretaría de Ciencia, Humanidades, Tecnología e Innovación (SECIHTI), Ciudad de México, México.

4 Grupo de Investigación “One Health”, Laboratorio de Zoología, Facultad de Ciencias Biológicas, Universidad Ricardo

Palma, Lima, Perú.

5 Grupo de Investigación en Sostenibilidad Ambiental (GISA), Facultad de Ciencias Naturales y Matemática, Universidad

Nacional Federico Villarreal, Lima, Perú.

6 Centro de Estudios Tecnológicos del Mar No. 29, Academia de Acuacultura, Ciudad del Carmen, Campeche, México.

7 Medicina Veterinaria de la Universidad Intercultural del Estado de Puebla, Ahuacatlán (UIEPA), Ahuacatlán, Puebla,

México.

8 Unidad Guaymas, Centro de Investigaciones Biológicas del Noroeste, Guaymas, Sonora, México.

* Corresponding author: marodriguezsa@secihti.mx

Celso Rubén Canche-Tun: https://orcid.org/0000-0001-5118-5058

María Amparo Rodríguez-Santiago: https://orcid.org/0000-0003-0616-237X

Enrique Ávila: https://orcid.org/0000-0001-7074-1603

José Iannacone: https://orcid.org/0000-0003-3699-4732

Stephanie Córdova-Osorio: https://orcid.org/0009-0000-8440-1431

Deysi Medrano-Domínguez: https://orcid.org/0009-0001-4668-7966

Ianna Guzmán-Medrano: https://orcid.org/0009-0005-0447-5593

Mario Loya-Bautista: https://orcid.org/0009-0009-9970-9194

Juan Manuel Osuna-Cabanillas: https://orcid.org/0000-0002-3959-0592

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ABSTRACT

e Mayan cichlid, Mayaheros urophthalmus (Günther, 1862), is a euryhaline ﬁsh used for local consumption in

southeastern Mexico. is study characterized larval anisakid nematodes in ﬁsh sold at a market in Ciudad del Carmen,

Campeche, and assessed their potential relevance to food safety. Fifteen ﬁsh obtained from market vendors were

transported on ice and examined for external and internal parasites. Nematodes were cleared in glycerin and identiﬁed

morphologically. Contracaecum sp. occurred in 3 of 15 ﬁsh (prevalence = 20.0%), Anisakis sp. morphotype I in 5 of 15

(33.3%), and Anisakis sp. morphotype II, tentatively assigned to the A. simplex sensu lato complex, in 2 of 15 (13.3%).

At least one anisakid larval morphotype occurred in 8 of 15 ﬁsh, yielding an overall larval prevalence of 53.3%. Free

nematode eggs were observed in 4 of 15 ﬁsh (occurrence = 26.7%) and were reported separately because they could

not be assigned to a taxon. Larvae were recovered from the mesenteries and peritoneum, where they were generally

encapsulated, and from the external surface or wall of the stomach and intestine. Because the edible musculature was

not examined separately and species-level identiﬁcation was not conﬁrmed molecularly, consumer exposure and the

probability of human infection cannot be estimated. e ﬁndings document anisakid larvae in ﬁsh sold for consumption

and support molecular identiﬁcation, systematic examination of edible muscle, prompt evisceration, and parasitological

surveillance of local ﬁshery products.

Keywords: anisakids – food safety – marked ﬁsh – Mayan cichlid – zoonotic potential

RESUMEN

La mojarra castarrica, Mayaheros urophthalmus (Günther, 1862), es un pez eurihalino utilizado para el consumo local en

el sureste de México. El objetivo fue caracterizar larvas de nematodos anisákidos en peces comercializados en un mercado

de Ciudad del Carmen, Campeche, y evaluar su relevancia potencial para la inocuidad alimentaria. Se obtuvieron 15

peces de vendedores del mercado, se transportaron con hielo y se examinaron para detectar parásitos externos e internos.

Los nematodos se aclararon en glicerina y se identiﬁcaron morfológicamente. Contracaecum sp. se encontró en 3 de

15 peces (prevalencia = 20,0%); Anisakis sp. morfotipo I, en 5 de 15 (33,3%) y Anisakis sp. morfotipo II, asignado

tentativamente al complejo A. simplex sensu lato, en 2 de 15 (13,3%). Al menos un morfotipo larvario de anisákido se

encontró en 8 de 15 peces, con una prevalencia larvaria global de 53,3%. Se observaron huevos libres de nematodos en

4 de 15 peces (ocurrencia = 26,7%), los cuales se informaron por separado porque no pudieron asignarse a un taxón.

Las larvas se recuperaron de los mesenterios y del peritoneo, donde generalmente estaban encapsuladas, así como de

la superﬁcie externa o pared del estómago y del intestino. Dado que la musculatura comestible no se examinó por

separado y la identiﬁcación a nivel de especie no se conﬁrmó mediante análisis moleculares, no es posible estimar la

exposición del consumidor ni la probabilidad de infección humana. Los hallazgos documentan larvas de anisákidos en

peces destinados al consumo y respaldan la identiﬁcación molecular, el examen sistemático del músculo comestible, la

evisceración oportuna y la vigilancia parasitológica de los productos pesqueros locales.

Palabras clave: anisákidos – inocuidad alimentaria – mojarra castarrica – peces de mercado – potencial zoonótico

INTRODUCTION

As in many aquatic ecosystems, ﬁsh are exposed to parasitic

infections that may have both ecological and sanitary

implications (Rodríguez-Santiago et al., 2014; Laﬀerty &

Mordecai, 2016; Poulin, 2019; Rodríguez-Santiago et al.,

2019; Hasik et al., 2025). Parasites in ﬁshery products

have become an increasing concern for public health in

several regions worldwide (Garrido-Olvera et al., 2022;

Rodríguez-Santiago et al., 2022). In the southern Gulf

of Mexico, this issue has gained relevance due to the

risks associated with the consumption of contaminated

ﬁsh and the growing incidence of zoonotic diseases

(Rodríguez-Santiago et al., 2026).

Factors such as water quality conditions, inadequate

control during ﬁsh handling, cleaning and preservation

processes, as well as the traditional consumption of

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raw or undercooked seafood products, signiﬁcantly

contribute to the transmission of parasites that may aﬀect

human health (Garrido-Olvera et al., 2022; Rodríguez-

Santiago et al., 2022). During recent decades, parasitism

has been recognized as a fundamental ecological process,

regulating host population abundance and density,

stabilizing trophic networks, and contributing to the

structuring of animal communities (Dunn et al., 2019;

Hasik et al., 2025).

In Mexico, ﬁshes, particularly freshwater species,

constitute the most extensively studied host group

regarding helminth parasites (Rodríguez-Santiago et

al., 2022). e National Helminth Collection contains

approximately 4,000 records from nearly 200 freshwater

ﬁsh species, in which about 270 helminth species have

been documented (Choudhury et al., 2020; Mendoza-

Franco et al., 2018).

Aquatic ecosystems, particularly those characterized by

complex trophic webs, facilitate the transmission of para-

sites with indirect life cycles and support diverse parasite

assemblages. is pattern has been widely documented in

ﬁshes, which have received considerable attention in eco-

logical parasitology (Poulin, 2017; Carlson et al., 2020).

is attention is partly explained by the fact that ﬁshes are

often collected and examined in large numbers, thereby

increasing the probability of detecting their parasite fau-

na compared with other vertebrate groups. e Mayan

cichlid, Mayaheros urophthalmus (Günther, 1862), is con-

sidered a potential host for a wide variety of parasites be-

cause of its opportunistic feeding habits. Under natural

conditions, its diet consists mainly of small crustaceans,

insects, microalgae, and detritus. However, the species

can also adapt to artiﬁcial diets developed through nutri-

tional studies (Franco-López et al., 2021; Froese & Pauly,

2023; Rodríguez-Santiago et al., 2024).

Previous studies have identiﬁed a variety of parasites

infecting ﬁsh and mollusks, including trematodes,

cestodes, nematodes, and protozoans, some of which are

of zoonotic importance because of their ability to infect

humans through the consumption of raw or insuﬃciently

cooked products (Rodríguez-Santiago & Rosales-Casián,

2011; Rodríguez-Santiago et al., 2016; Shamsi, 2019).

In this context, it is necessary to characterize the parasite

species present in commercially important ﬁsh species

and to assess the potential risks they pose to consumers.

e Mayan cichlid, Mayaheros urophthalmus (Günther,

1862), is a ﬁsh species of high ecological, economic,

and nutritional importance in coastal regions of Mexico,

particularly in Ciudad del Carmen, Campeche. is

species not only represents an essential resource for local

food security but also supports ﬁsheries and commercial

activities of considerable regional importance (Fernández-

Pérez, 2024).

erefore, the present study aimed to characterize larval

anisakid nematodes in M. urophthalmus sold at a ﬁsh

market in Ciudad del Carmen, Campeche, Mexico,

estimate their prevalence, document their infection sites,

and assess their potential relevance to food safety within

the limitations of morphological identiﬁcation and the

absence of a speciﬁc examination of edible musculature.

MATERIALS AND METHODS

Study Area

Laguna de Términos is located in southeastern Mexico

and partially encompasses the municipalities of Carmen,

Escárcega, Champotón, Calakmul, and Candelaria in the

state of Campeche. e system covers an approximate area

of 4,676.33 km² and has a perimeter of 800.44 km. In

the southeastern portion of the basin, the terrain reaches

an elevation of 262 m above sea level (asl), whereas the

northern sector lies at sea level (CONAGUA, 2004).

e lagoon belongs to the Mamantel River watershed,

which is part of the Grijalva–Usumacinta Hydrological

Region (RH30) and the Administrative Region XII,

Yucatán Peninsula. In addition, it partially includes ﬁve

priority conservation regions: two hydrological regions

(Laguna de Términos, Pantanos de Centla, and Southern

Campeche), two terrestrial regions (Pantanos de Centla

and Silvituc-Calakmul), and one marine region (Pantanos

de Centla, Laguna de Términos) (RAMSAR, 2003).

e study was conducted at the Renovación Market,

locally known as “El Chechén”, in Ciudad del Carmen,

Campeche, Mexico (18°38′54.60″ N, 91°47′36.77″ W).

Fifteen specimens of M. urophthalmus were donated by

Pescadería Doña Mari, one of the ﬁsh stalls located in

the market. According to information provided by the

vendor, the ﬁsh originated from diﬀerent geographic

locations along the Palizada River. e specimens were

transported on ice to the Environmental Parasitology

Laboratory of the Institute of Marine Sciences and

Limnology, El Carmen Station, National Autonomous

University of Mexico. e market constituted the

sampling site, and the precise capture locality of each ﬁsh

was not independently veriﬁed (Fig. 1).

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Figure 1. Location of the study area. (a) Geographic location of Mexico. (b) Extent of the Laguna de Términos Flora

and Fauna Protection Area, Campeche. (c) e circle indicates the study site corresponding to the “Chechén” market in

Ciudad del Carmen, Campeche.

Fish collection

A total of 15 fresh specimens of the Mayan cichlid,

M. urophthalmus, were obtained considering their

commercial importance in the region. Sampling was

conducted in collaboration with local ﬁshermen and

seafood vendors, who provided specimens purchased

from a stall at the Renovación Market, locally known as

“El Chechén”, for laboratory examination (Fig. 2).

Fish were captured using No. 6 trawl nets, with ﬁshing

operations lasting between 45 and 90 min. Subsequently,

the specimens were transported on ice to the

Environmental Parasitology Laboratory of the Institute

of Marine Sciences and Limnology, “El Carmen” Station,

National Autonomous University of Mexico (UNAM),

where the parasitological examination was conducted.

Diagnosis of internal parasites

e dissection procedure for the collection of

endoparasites began with an incision along the lateral

line of each ﬁsh, followed by the immediate removal

of the gills. Subsequently, an incision was made in the

abdominal cavity, extending from the cloaca to the

branchial region using straight-tipped scissors. e

entire digestive tract, from the oral-branchial region to

the rectum, was removed and placed in a Petri dish for

examination (Keim, 1982; Aho et al., 2018) (Fig. 2).

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e remaining internal organs, including the spleen,

gallbladder, urinary bladder, stomach, intestines, kidneys,

swim bladder, liver, mesenteries, adipose tissues, brain,

and eyes, were also dissected and individually placed

in Petri dishes containing 0.7% saline solution (Keim,

1982; Möller & Anders, 1986) (Fig. 2).

For parasite detection, the diﬀerent organs were examined

under a stereoscopic microscope. Each organ (except

the eyes) was compressed between two glass slides using

the compression technique to facilitate observation and

determine the presence or absence of parasites (Fig. 2).

External Examination

Each specimen was subjected to a washing and sieving

procedure using a 0.3 mm (300 µm) mesh to recover

ectoparasites. is technique consisted of placing the ﬁsh

on a sieve and carefully washing it with running water

for approximately 2 minutes per specimen. e material

retained on the sieve was subsequently examined for the

presence of ectoparasites (Fig. 2).

Internal Examination

e dissection for endoparasite collection began with

an incision along the lateral line of the ﬁsh, followed

by the immediate removal of the gills. Subsequently, an

incision was made in the abdominal cavity, extending

from the cloaca to the branchial region using straight-

point scissors. e entire digestive tract, from the oral-

branchial region to the rectum, was removed and placed

in a Petri dish for examination (Fig. 2).

e remaining internal structures, including the spleen,

gallbladder, urinary bladder, stomach, intestines, kidneys,

swim bladder, liver, mesenteries, adipose tissues, brain,

and eyes, were also dissected and individually placed in

Petri dishes containing 0.7% saline solution.

For analysis, the diﬀerent organs were examined under

a stereoscopic microscope. Each organ (except the eyes)

was placed between two microscope slides using the

compression technique to facilitate observation and

determine the presence or absence of parasites. Internal

parasites (endoparasites) were isolated and placed in

Eppendorf vials containing 70% ethanol for initial

preservation. Subsequently, nematode specimens were

transferred to 50% glycerin for clariﬁcation, allowing

detailed observation under a light microscope and

subsequent taxonomic identiﬁcation (Fig. 2).

Taxonomic Identiﬁcation

For taxonomic identiﬁcation, nematodes (Nematoda)

were cleared using gradual glycerin solutions following

the methodology proposed by Moravec et al. (1993).

Specimens were then mounted on microscope slides with

coverslips and examined under a light microscope for

identiﬁcation using specialized taxonomic keys. Finally,

all records were incorporated into a parasitological

database, and the specimens were deposited in the

Parasitology Collection of the Environmental Parasitology

Laboratory, Institute of Marine Sciences and Limnology,

“El Carmen” Station, National Autonomous University

of Mexico (UNAM), Mexico (Fig. 2).

Preparation of Parasitological Illustrations

e illustrations of the identiﬁed parasites were produced

using a combination of traditional drawing and digital

editing techniques. Initially, a hand-drawn sketch was

created based on the morphological characteristics

observed in the specimens and on previously published

taxonomic descriptions. e sketch was then

photographed using a mobile phone camera, and the

digital image was imported into the software Ibis Paint X.

Once imported, multiple digital layers were used to trace

the outlines and morphological details of each organism,

allowing for a more accurate representation of diagnostic

structures. Finally, digital colors were applied to reproduce

the staining observed in the microscopic preparations,

resulting in digital illustrations that were used to

complement the identiﬁcation and documentation of the

parasites recorded in this study.

Data analysis

Prevalence was calculated as the number of ﬁsh infected

with a given larval morphotype divided by the 15 ﬁsh

examined and multiplied by 100, following Bush et al.

(1997). Overall larval prevalence was calculated from

the number of ﬁsh harboring at least one anisakid

larval morphotype. Free nematode eggs were reported

separately as occurrence because they were not assigned to

a parasite taxon. Percentages describing the distribution

of larvae among positive ﬁsh were treated as descriptive

proportions and not as prevalence. Mean abundance and

mean intensity were not calculated because the taxon-

speciﬁc raw counts could not be veriﬁed consistently

from the available records.

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Canche-Tun et al.

Ethical considerations

 e study used ﬁ sh that had already been captured

and oﬀ ered for sale for human consumption.  e

research team did not capture, maintain, experimentally

manipulate, or euthanize live vertebrates speciﬁ cally for

this investigation.

RESULTS

Larval anisakids were detected in 8 of the 15 examined

ﬁ sh, corresponding to an overall larval prevalence of

53.3%.  ree larval morphotypes were recognized:

Contracaecum sp., Anisakis sp. morphotype I, and

Anisakis sp. morphotype II, tentatively assigned to the A.

simplex sensu lato complex (Fig. 3). Free nematode eggs

were observed in four ﬁ sh and were analyzed separately

(Table 1).

 e larvae were located in the mesenteries and

peritoneum, where they were generally encapsulated, and

on or within the external surface or wall of the stomach

and intestine. No conclusion can be made regarding

infection of edible muscle because the musculature was

not examined separately.

Contracaecum sp. was recorded in three ﬁ sh, with M7

accounting for 51.6% of the larvae assigned to this

morphotype, M2 for 38.7%, and M10 for 9.7%. Anisakis

sp. morphotype I occurred in ﬁ ve ﬁ sh; the proportional

distribution was 26.3% in M3, 21.1% in M1 and M2,

and 15.8% in M4 and M7. Morphotype II occurred in

M9 and M5, which accounted for 71.4% and 28.6%,

respectively.  ese percentages describe the proportional

distribution of each morphotype among positive ﬁ sh and

are not prevalence values.

Free nematode eggs were detected in M3, M7, M8, and

M9, corresponding to an occurrence of 26.7%.  ey were

not pooled with the larval morphotypes because their

taxonomic identity and association with adult nematodes

could not be established.

Figure 2. Methodological scheme of the parasitological analysis performed on Mayaheros urophthalmus.

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Table 1. Prevalence of anisakid larval morphotypes and occurrence of free nematode eggs in 15 market-sold Mayaheros

urophthalmus.

Taxon or ﬁnding Positive ﬁsh Positive ﬁsh

(n)

Prevalence or

occurrence (%)

Contracaecum sp. M2, M7, M10 3 20.0

Anisakis sp. morphotype I M1, M2, M3, M4, M7 5 33.3

Anisakis sp. morphotype II, cf. A. simplex

s.l. M5, M9 2 13.3

Any anisakid larval morphotype M1, M2, M3, M4, M5,

M7, M9, M10 8 53.3

Free nematode eggs* M3, M7, M8, M9 4 26.7

Occurrence is reported instead of taxon-speciﬁc prevalence because the eggs were not identiﬁed to genus or species.

DISCUSSION

ree larval nematode taxa were identiﬁed in M.

urophthalmus: Contracaecum sp., Anisakis sp. morphotype

I, and Anisakis sp. morphotype II, the latter tentatively

assigned to the Anisakis simplex sensu lato complex.

Nematode larvae were detected in eight of the 15 ﬁsh

examined, corresponding to an overall prevalence

of 53.3%. Among the identiﬁed taxa, Anisakis sp.

morphotype I showed the highest prevalence (33.3%),

followed by Contracaecum sp. (20.0%) and Anisakis sp.

Figure 3. Illustrations of the internal structures of the three parasite species identiﬁed in the present study. (A)

Contracaecum sp., (B) Anisakis sp. morphotype I, and (C) Anisakis sp. morphotype II.

morphotype II (13.3%). ese ﬁndings indicate that

more than half of the Mayan cichlids marketed in Ciudad

del Carmen harbored trophically transmitted anisakid

larvae and support the participation of M. urophthalmus

as an intermediate or paratenic host in aquatic food webs

of southeastern Mexico (Rodríguez-Santiago et al., 2024).

Mayaheros urophthalmus is widely distributed in freshwater

and brackish environments of southeastern Mexico, where

it contributes to artisanal ﬁsheries and local consumption.

Its opportunistic and predominantly omnivorous diet

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Canche-Tun et al.

includes small crustaceans, insects, detritus, and other

aquatic organisms that may participate as intermediate

hosts in helminth life cycles. Consequently, its feeding

ecology may facilitate exposure to infective nematode

larvae in the ﬂuvial, lagoon, mangrove, and estuarine

environments characteristic of the region (Franco-López

et al., 2021; Rodríguez-Santiago et al., 2024).

e occurrence of Contracaecum sp. agrees with previous

records in freshwater and estuarine ﬁshes. Bullard

et al. (2004) reported larval Contracaecum sp. in M.

urophthalmus from Florida, conﬁrming that this ﬁsh can

participate in the transmission cycle of the nematode

under diﬀerent environmental conditions. In the present

study, Contracaecum sp. showed a prevalence of 20.0%, a

value within the range reported for juvenile gray snapper,

Lutjanus griseus, from Mecoacán Lagoon, Tabasco.

Rodríguez-Santiago et al. (2022) recorded prevalences

ranging from 3.3 to 23.3% for two Contracaecum

morphotypes, depending on the morphotype and

sampling season. ese comparable values indicate that

exposure to Contracaecum larvae occurs in diﬀerent

coastal lagoon systems of the southern Gulf of Mexico,

although prevalence may vary according to host species,

season, diet, and the local availability of infected prey.

e occurrence of Contracaecum larvae in ﬁshes from

Campeche and Tabasco may reﬂect trophic transmission

within the complex aquatic food webs of southeastern

Mexico. Species of this genus have indirect life cycles

in which aquatic invertebrates and ﬁshes may act as

intermediate or paratenic hosts, whereas piscivorous

birds generally serve as deﬁnitive hosts (Buchmann &

Mehrdana, 2019). Ecological connectivity among rivers,

coastal lagoons, mangroves, and estuarine environments

may facilitate contact among the hosts involved in these

transmission cycles. However, neither intermediate

nor deﬁnitive hosts nor environmental stages of the

parasite were evaluated in the present study. erefore,

this interpretation should be regarded as a plausible

ecological explanation rather than a demonstrated causal

relationship.

e detection of Anisakis morphotypes is particularly

relevant because members of this genus are mainly

associated with marine food webs. eir life cycles

involve aquatic invertebrates as intermediate hosts, ﬁshes

and cephalopods as intermediate or paratenic hosts, and

marine mammals as deﬁnitive hosts (Mattiucci et al.,

2018; Buchmann & Mehrdana, 2019). e occurrence

of Anisakis larvae in M. urophthalmus may therefore

reﬂect ecological connectivity among freshwater,

estuarine, and marine environments in the southern

Gulf of Mexico, possibly through the consumption

of infected crustaceans or small ﬁshes. Nevertheless,

although vendors indicated that the examined ﬁsh

originated from diﬀerent areas of the Palizada River,

the precise capture locations could not be veriﬁed.

Consequently, the speciﬁc environment in which the

infections were acquired remains unknown.

Anisakis sp. morphotype I showed a prevalence of 33.3%,

whereas morphotype II, tentatively assigned to the

A. simplex sensu lato complex, showed a prevalence of

13.3%. ese records provide preliminary evidence that

M. urophthalmus is exposed to anisakid transmission cycles

in southeastern Mexico. However, species belonging to

the A. simplex complex cannot be reliably diﬀerentiated

solely through larval morphology because closely related

taxa share several diagnostic characteristics. Molecular

analyses are therefore required before these larvae can

be conclusively assigned to A. simplex (Mattiucci et al.,

2018).

e anisakid larvae were recovered from the mesenteries

and peritoneum, where they were generally encapsulated,

as well as from the surface or wall of the stomach and

intestine. ese infection sites agree with the visceral

distribution of anisakid larvae documented in other

commercially important ﬁshes. Rodríguez-Santiago et

al. (2016) recorded anisakids in the mesentery, coelomic

cavity, stomach wall, intestine, and other visceral organs

of Caulolatilus princeps and Sebastes miniatus. e visceral

and encapsulated locations observed in M. urophthalmus

are therefore consistent with larval migration and

establishment following the ingestion of infected prey.

Diﬀerences in anisakid prevalence among ﬁsh species may

be associated with host diet, trophic position, mobility,

and the availability of infected prey. Marine predatory

ﬁshes commonly consume crustaceans, cephalopods,

and small ﬁshes that may accumulate anisakid larvae,

whereas M. urophthalmus has a more generalist and

opportunistic diet. Environmental conditions, including

temperature, salinity, habitat connectivity, and the

distribution of intermediate and deﬁnitive hosts, may

also inﬂuence parasite transmission (Mattiucci et al.,

2018; Rahmati et al., 2020; Sures & Nachev, 2022; Sures

et al., 2023). e extensive ﬂuvial, lagoon, and estuarine

systems of southeastern Mexico are characterized by

marked salinity gradients and seasonal variation in

precipitation and freshwater discharge. However, because

these environmental variables were not measured,

their inﬂuence on the observed prevalence cannot be

determined from the present data.

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Neotropical Helminthology, Vol. 20, Nº2, jul - dec 2026

From a public health perspective, the detection of Anisakis

and Contracaecum larvae indicates potential zoonotic

relevance because species belonging to these genera

have been associated with gastrointestinal or allergic

manifestations in humans following exposure to infected

ﬁsh products (Audicana & Kennedy, 2008; Shamsi &

Suthar, 2016; Buchmann & Mehrdana, 2019). Larvae

and allergens associated with the A. simplex complex may

cause abdominal symptoms, urticaria, and, in sensitized

individuals, anaphylactic reactions (Daschner & Pascual,

2005; Hernández-González et al., 2023). e detection

of anisakid larvae in ﬁsh marketed in Ciudad del Carmen

therefore highlights the importance of parasitological

surveillance of ﬁshery products intended for local

consumption.

Nevertheless, the observed prevalence should not be

interpreted as an equivalent probability of human

infection. All larvae were recovered from visceral tissues,

and the edible musculature was not examined separately.

Consequently, the present results do not demonstrate

the occurrence of infective larvae in the portions of

the ﬁsh normally consumed by humans. In some ﬁsh

species, anisakid larvae may migrate from the viscera to

the musculature after host death, although the extent of

this process depends on the parasite and host species,

storage temperature, and time elapsed before evisceration

(Rodríguez-Santiago et al., 2016; Shamsi & Barton,

2023). Prompt evisceration, adequate refrigeration,

prevention of cross-contamination, and thorough

cooking are therefore appropriate measures for reducing

potential exposure to viable larvae. However, some

anisakid allergens may remain active after thermal or

freezing treatments, particularly in previously sensitized

individuals (Audicana & Kennedy, 2008; Hernández-

González et al., 2023).

e present study expands the limited information

available on the parasite fauna of M. urophthalmus in

southeastern Mexico. A previous investigation conducted

on Isla del Carmen documented ectoparasitic crustaceans

in this host and emphasized the scarcity of parasitological

information for the species in the region (Rodríguez-

Santiago et al., 2024). e present ﬁndings complement

those records by documenting larval anisakid nematodes

in Mayan cichlids marketed in Ciudad del Carmen.

e small sample size of 15 ﬁsh limits the precision and

regional representativeness of the prevalence estimates.

Moreover, the lack of veriﬁed capture locations prevents

the association of infections with particular environmental

conditions or aquatic systems. Future studies should

include larger and seasonally replicated samples from

documented capture localities, separate examination

of viscera and edible musculature, and molecular

identiﬁcation of the recovered larvae. Incorporating host

diet and environmental variables would also improve

understanding of the spatial and temporal dynamics of

anisakid transmission and its potential implications for

food safety in the southern Gulf of Mexico.

e present study documents the occurrence of three lar-

val nematode taxa, Contracaecum sp., Anisakis sp. mor-

photype I, and Anisakis sp. morphotype II, the latter ten-

tatively assigned to the Anisakis simplex sensu lato com-

plex in the Mayan cichlid, M. urophthalmus, marketed in

Ciudad del Carmen, Campeche. Larval nematodes were

detected in eight of the 15 ﬁsh examined, corresponding

to an overall prevalence of 53.3%. ese ﬁndings support

the participation of M. urophthalmus as an intermediate

or paratenic host in the trophic transmission of anisakid

nematodes within aquatic food webs of southeastern

Mexico.

e occurrence of Anisakis and Contracaecum larvae

indicates potential zoonotic relevance and highlights

the importance of parasitological surveillance of ﬁshery

products intended for local consumption. However,

because all larvae were recovered from visceral tissues,

the edible musculature was not examined separately, and

identiﬁcation was based exclusively on morphological

characteristics. e present study does not demonstrate

the occurrence of infective larvae in edible tissues or allow

a direct estimation of the risk to consumers.

Overall, these ﬁndings expand current knowledge of

the parasite fauna of M. urophthalmus and provide

preliminary information on anisakid transmission in the

southern Gulf of Mexico. Future studies should include

larger and seasonally replicated samples from veriﬁed

capture localities, separate examination of viscera and

edible musculature, and molecular identiﬁcation of

the recovered larvae. ese approaches will help clarify

spatial and temporal patterns of infection and strengthen

parasitological monitoring and food-safety strategies for

ﬁshery products commercialized in southeastern Mexico.

ACKNOWLEDGEMENTS

is study was conducted at the Institute of Marine

Sciences and Limnology of the National Autonomous

University of Mexico (ICML-UNAM). e authors

gratefully acknowledge the support provided by the

SECIHTI project CIR/044/2024, “Biodiversity of

268

Neotropical Helminthology, Vol. 20, Nº2, jul - dec 2026

Canche-Tun et al.

parasites in aquatic organisms of the southern Gulf of

Mexico”, and by the PAPIIT-UNAM project IN203419,

“Biodiversity of marine sponges in subtidal environments

of Campeche State”, both of which were fundamental to

the development of this research. We express our sincere

gratitude to Enrique Ávila and María Amparo Rodríguez

Santiago for their academic guidance, continuous

support, and for providing the equipment necessary to

conduct this study. We thank José Francisco Eduardo

Velueta Centella for preparing the parasite illustrations

that were fundamental to the visual presentation of the

results. We also extend special recognition to Andrés Reda

Deara and Hernán Álvarez Guillén for their technical

assistance during ﬁeld sampling activities. Finally, we

acknowledge the participation of students from Colegio

Morelos Lizardi in both ﬁeld and laboratory activities,

particularly Berenice Martínez Martínez and Sebastián

Santiago Gordillo, whose enthusiasm, dedication,

and commitment signiﬁcantly contributed to the

development of this study. We also thank the school

authorities, especially Director Rubén Pérez de la Vega,

for their support and for fostering collaboration between

institutions, which strengthened student training

and enriched the scientiﬁc work carried out in this

investigation.

Author contributions: CRediT (Contributor Roles

Taxonomy)

CRCT = Celso Ruben Canche-Tun

MARS = María Amparo Rodríguez-Santiago

EÁ = Enrique Ávila

JI = José Iannacone

SCO = Stephanie Córdova-Osorio

DMD = Deysi Medrano-Domínguez

IGM= Ianna Guzmán-Medrano

MLB = Mario Loya-Bautista

JMOC = Juan Manuel Osuna-Cabanillas

Conceptualization: CRCT, MARS, SCO

Data curation: CRCT, MARS

Formal Analysis: CRCT, MARS, SCO

Funding acquisition: CRCT, MARS, SCO

Investigation: CRCT, MARS, SCO

Methodology: CRCT, MARS, SCO, DMD, MLB, IGM

Project administration: MARS, EÁ

Resources: EA, MARS

Software: CRCT, MARS, EÁ, JMOC, IGM

Supervision: MARS, EÁ, JI, JMOC, MLB

Validation: CRCT, MARS, EÁ, JMOC

Visualization: CRCT, MARS, EÁ, JMOC, MLB

Writing – original draft: SCO, CRCT, MARS

Writing – review & editing: CRCT, MARS, JI

BIBLIOGRAPHIC REFERENCES

Aho, J. M., Bush, S. E., Fernández, J. C., Kinsella, J.

M., Laﬀerty, K. D., Lotz, J. M., & Shostak, A. W.

(2018). Basic methods to study ﬁsh parasites. ABC

Taxa, 18, 89–130.

Audicana, M. T., & Kennedy, M. W. (2008). Anisakis

simplex: From obscure infectious worm to inducer

of immune hypersensitivity. Clinical Microbiology

Reviews, 21, 360–379.

Buchmann, K., & Mehrdana, F. (2019). Anisakis

nematodes in ﬁsh and shellﬁsh- from infection

to allergies. Food and Waterborne Parasitology, 17,

e00045.

Bullard, S.A., Barse, A.M., Curran, S.S., & Morris, J.A.,

Jr. (2004). First record of larval Contracaecum

sp. (Nematoda: Anisakidae) in Mayan cichlids

(Cichlasoma urophthalmus) from Florida, USA.

Journal of Parasitology, 90, 405–407.

Bush, A.O., Laﬀerty, K.D., Lotz, J.M. & Shostak,

A.W. (1997). Parasitology meets ecology on its

own terms: Margolis et al. revisited. Journal of

Parasitology, 83, 575–583.

Carlson, C.J., Dallas, T.A., Alexander, L.W., Phelan,

A.L., & Phillips, A.J. (2020). What would it

take to describe the global diversity of parasites?

Proceedings of the Royal Society B: Biological

Sciences, 287, 20201841.

Choudhury, A., Brooks, D.R., & Pérez-Ponce de León, G.

(2020). Helminths of freshwater ﬁshes of Mexico:

A review and synthesis. ZooKeys, 992, 1–125.

Comisión Nacional del Agua (CONAGUA). (2004).

Irrigation districts. General Subdirectorate of

Hydro-Agricultural Infrastructure.

Daschner, A., & Pascual, C. Y. (2005). Anisakis simplex:

Sensitization and clinical allergy. Current Opinion

in Allergy and Clinical Immunology, 5, 281–285.

Dunn, A.M., Torchin, M.E., Hatcher, M.J., Kotzenberg,

R., & Littlewood, D.T.J. (2019). Parasites and

269

Nematodes of the Mayan cichlid sold in Ciudad del Carmen

Neotropical Helminthology, Vol. 20, Nº2, jul - dec 2026

global change: Emerging issues and accelerating

impacts. Trends in Parasitology, 35, 705–718.

Fernández-Pérez, M. (2024). e Mayan Cichlid,

Mayaheros urophthalmus: Native Mesoamerican

species, with high aquaculture potential. Tropical

Aquaculture, 2, 37-62.

Franco-López, J., Pineda-Peralta, M., & Mendoza-

Franco, E.F. (2021). Feeding ecology and trophic

interactions of cichlid ﬁshes in southeastern

Mexico. Neotropical Ichthyology, 19, e210033.

Froese, R., & Pauly, D. (2023). FishBase. www.ﬁshbase.

org

Garrido-Olvera, L., García-Prieto, L., Osorio-Sarabia,

D., Sánchez-Martínez, J. G., Rábago-Castro, J.

L., Hernández-Mena, D. I., & de León, G. P. P.

(2022). Parasites with zoonotic potential found

in commercially important ﬁsh in Tamaulipas,

Northeastern Mexico. Parasitology International,

88, 102550.

Hasik, A. Z., Ilvonen, J. J., Gobbin, T. P., Suhonen, J.,

Beaulieu, J. M., Poulin, R., & Siepielski, A. M.

(2025). Parasitism as a driver of host diversiﬁcation.

Nature Reviews Biodiversity, 1, 401–410.

Hernández-González, A., Ceberio, A., & Audicana, M.T.

(2023). Allergy and Anisakis: e role of allergens

and host response. Pathogens, 12, 505.

Keim, A. (1982). Manual de métodos parasitológicos e

histopatológicos en piscicultura. Organización de

las Naciones Unidas para la Alimentación y la

Agricultura (FAO).

Laﬀerty, K.D., & Mordecai, E.A. (2016). e rise and

fall of infectious disease in a warmer world. e

Lancet Planetary Health, 1, e8–e9.

Mattiucci, S., Cipriani, P., Levsen, A., Paoletti, M., &

Nascetti, G. (2018). Molecular epidemiology

of Anisakis and anisakiasis: An ecological and

evolutionary road map. Advances in Parasitology,

99, 93–263.

Mendoza-Franco, E.F., Caspeta-Mandujano, J.M., &

Vidal-Martínez, V.M. (2018). Helminth parasites

of freshwater ﬁshes in Mexico: Recent advances

and perspectives. Journal of Helminthology, 92,

649–664.

Möller, H., & Anders, K. (1986). Diseases and parasites of

marine ﬁshes. Verlag Möller.

Moravec, F., Kohn, A., & Fernandes, B. M. M. (1993).

Nematode parasites of ﬁshes of the Paraná

River, Brazil. Part 2. Seuratoidea, Ascaridoidea.

Habronematoidea and Acuarioidea. Folia

Parasitológica, 40, 115–134.

Poulin, R. (2017). Evolutionary ecology of parasites (2nd

ed.). Princeton University Press.

Poulin, R. (2019). e many roads to parasite

specialization. Ecology Letters, 22, 5–22.

Rahmati, A. R., Kiani, B., Afshari, A., Moghaddas, E.,

Williams, M., & Shamsi, S. (2020). Worldwide

prevalence of Anisakis larvae in ﬁsh and its

relationship to human allergic anisakiasis: A

systematic review. Parasitology Research, 119,

3585–3594.

RAMSAR. (2003). Ramsar Information Sheet (RIS),

Laguna de Términos Flora and Fauna Protection

Area. https://rsis.ramsar.org/ris/1356.

Rodríguez-Santiago, M.A., & Rosales-Casián, J.A.

(2011). Parasite structure of the ocean whiteﬁsh

Caulolatilus princeps from Baja California, Mexico

(East Paciﬁc). Helgoland Marine Research, 65,

197–202.

Rodríguez-Santiago, M.A., Rosales-Casián, J.A., &

Grano-Maldonado, M.I. (2014). Dynamics of

a parasite assemblage of the vermilion rockﬁsh

Sebastes miniatus from northwestern Baja

California, Mexico. Helgoland Marine Research,

68, 299–306.

Rodríguez-Santiago, M.A., Rosales-Casián, J.A., &

Grano-Maldonado, M.I. (2016). Anisakinae

nematodes in two commercial marine ﬁsh from

the East Paciﬁc of Baja California, Mexico. Paciﬁc

Science, 70, 243–250.

Rodríguez-Santiago, M.A., García-Magaña, L., Grano-

Maldonado, M.I., Silva-Martínez, E.N., Guerra-

Santos, J., & Gelabert, R. (2019). First record

of Trichodina centrostrigeata Basson, Van As &

Paperna, 1983 (Ciliophora: Trichodinidae) from

Oreochromis niloticus (Linnaeus, 1758) cultured

in southeastern Mexico. Latin American Journal of

Aquatic Research, 47, 367–370.

Rodríguez-Santiago, M. A., Ramos-Colorado, L.,

García-Magaña, L., Grano-Maldonado, M. I.,

Iannacone, J., & Vázquez-Caballero, A. (2022).

Parasite community analysis of the gray snapper

Lutjanus griseus (Perciformes, Lutjanidae) in a

tropical region of the Southern Gulf of Mexico.

Helminthologia, 59, 94–103.

270

Neotropical Helminthology, Vol. 20, Nº2, jul - dec 2026

Canche-Tun et al.

Rodríguez-Santiago, M.A., Canche-Tun, C.R., Ávila,

E., Iannacone, J.A., & Argota-Pérez, G. (2024).

Ectoparasites of the Mayan cichlid Mayaheros

urophthalmus (Günther, 1862) (Cichliformes:

Cichlidae) in a mangrove ecosystem of southeastern

Mexico. SIBIUAS Revista de la Dirección General

de Bibliotecas, 4, 12–23.

Rodríguez-Santiago, M. A., García-Prieto, L., Ávila,

E., Gelabert-Fernández, R., Iannacone-Oliver,

J., Argota-Pérez, G., Caballero-Vázquez, J. A.,

Capparelli, M., Canales-Delgadillo, J. C., Celis-

Hernández, O., & Gómez-Ponce, M. A. (2026).

Uso de parásitos de organismos acuáticos como

potenciales bioindicadores de salud ambiental en la

Laguna de Términos. En 30 años de estudio de

la Laguna de Términos (capítulo de libro). En

prensa.

Shamsi, S. (2019). Parasite risk associated with

consumption of raw ﬁsh and seafood. Reviews in

Food Safety, 18, 1–12.

Shamsi, S., & Barton, D. P. (2023). A critical review of

anisakidosis cases occurring globally. Parasitology

Research, 122, 1733–1745.

Shamsi, S., & Suthar, J. (2016). Eﬀects of anisakid

nematodes Anisakis simplex (s.l.), Pseudoterranova

decipiens (s.l.) and Contracaecum osculatum (s.l.)

on ﬁsh and consumer health. Food and Waterborne

Parasitology, 4, 13–22.

Sures, B., & Nachev, M. (2022). Parasites as useful

sentinels for environmental pollution.

International Journal for Parasitology: Parasites

and Wildlife, 17, 181–189.

Sures, B., Nachev, M., & Zimmermann, S. (2023).

Environmental parasitology: Parasites as indicators

of environmental stress and ecosystem health.

Trends in Parasitology, 39, 1–12.

Received June 8, 2026.

Accepted August 5, 2026.

Published online August 5, 2026.