Camallanus cotti Fujita, 1927 (Nematoda, Camallanoidea) in ornamental aquarium fishes: pathology and morphology

Abstract

Ornamental fishes are of increasing economic importance worldwide taking into account the continuous trade involving several species that are either exported or imported from a couple of countries, mostly from Asia (Evans & Lester 2001, Kim et al. 2005. The importation generally involves the introduction of exotic parasites that can affect a large number of hosts and the detection of parasitism is an important step to avoid the spreading of fish diseases among the native fauna. This paper deals with the first data on the pathology induced by the exotic nematode Camallanus cotti Fujita, 1927 in two species of ornamental fishes kept in an aquarium in Niterói, state of Rio de Janeiro, Brazil; C. cotti is briefly redescribed and figured. MATERIALS AND METHODSFive adult guppies [Poecilia reticulata (Peters, 1859)] three males and two females and two adult females of the beta fish [Betta splendens (Regan, 1910)] were investigated for helminths. The fishes were kept in a home aquarium, for two months and had been purchased in a pet shop located in Niterói, state of Rio de Janeiro, Brazil. The guppies formerly derived from a fish farmer maintained in the state of São Paulo, Brazil. Fishes were necropsied in accordance with ethical procedures and dissected organs kept in Petri dishes with a 0.85% NaCl solution for the recovery of worms under a stereoscope microscope. Nematodes were fixed with steaming AFA (70º GL ethanol, 93%; formaldehyde, 5%; glacial acetic acid, 2%) and stored as wet material in the same solution; some were further dehydrated in an ethanol series, clarified in glacial acetic acid, phenol and preserved as whole mounts in beechwood creosote and Canada balsam. A couple of parasites were stained with alcoholic chloride Langeron's carmine. Samples are deposited in the Helminthological Collection of the Oswaldo Cruz Institute (CHIOC). Portions of the parasitized intestines were removed and immediately fixed in 10% formalin, to be further routinely processed for paraffin embedding. Five micrometers thick sections were stained with hematoxylin and eosin (HE)."En face" jelly mounts of the nematodes were obtained in accordance with the method of Anderson (1958) and photomicrographs in a Zeiss Axiophot bright-field microscope with a Differential Interference Contrast (DIC) apparatus and in a Leica stereomicroscope (live parasites). Identification of the nematodes was based on data after Moravec and Nagasawa (1989). Measurements are in millimeters (mm) and means in parentheses. RESULTSThree of the five guppies and the two beta fishes examined were positive for nematodes.On what concerns clinical signs, fishes were apathetic and, in the male guppies, a reduction of the libido was observed. Two guppy and two beta fish females presented abdominal swelling with reddish parasites protruding from the anus (Fig. 1); beta fish females also showed anorexia. Microscopic lesions were similar in both fish species and consisted of hemorrhage, congestion, edema, a few glandular elements, and extensive erosion areas in the rect...

Camallanus cotti (Nematoda: Camallanidae), an introduced parasite of fishes in New Caledonia

“…It seems it was originally distributed in eastern, southeastern and southern Asia, from where it has been recorded from Japan, China, eastern Russia (Amur R. basin), Korea, Vietnam, Singapore and India (e.g., Fujita 1927a,b, Yamaguti 1935, Li 1941, Dogiel and Akhmerov 1959, Roytman 1963, Raina and Dhar 1972, Chen 1973, Petter et al 1974, Wang et al 1979, Wu 1984, Vismanis et al 1987, Moravec and Sey 1988, Moravec and Nagasawa 1989, Wu et al 1991, Kim et al 2002, Moravec et al 2003. It also occurs in the cultures of aquarium fishes in Europe, North America (Canada), South America (Brazil), West Indies (Puerto Rico) and Australia, where this pathogenic parasite is being brought in along with exotic fishes, imported mainly from Singapore (e.g., Schubert 1972, Petter et al 1974, Stumpp 1975, Campana-Rouget et al 1976, Bunkley-Williams and Williams 1994, Font and Tate 1994, Alves et al 2000, Evans and Lester 2001, Levsen 2001, Levsen and Berland 2002a,b, Levsen and Jakobsen 2002, Menezes et al 2006. Camallanus cotti has also been reported from native and introduced fishes in some streams in Hawaii, where it was apparently brought in along with the introduction of poeciliids (Font and Tate 1994, Font 1997a, b, 1998, 2003, Vincent and Font 2003a.…”

Population genetic structure of the parasitic nematode Camallanus cotti inferred from DNA sequences of ITS1 rDNA and the mitochondrial COI gene

“…Extensive studies have been carried out in relation to the nematode's taxonomy, faunal investigation, pathology, and population dynamics (e.g. Moravec and Nagasawa, 1989;McMinn, 1990;Moravec et al, 2003;Menezes et al, 2006;Wu et al, 2007). Despite these extensive researches, little is known about its population genetic structure.…”

Metazoan parasites of freshwater ornamental fishes

“…In Brazil, Camallanus cotti (Fujita, 1927) possibly introduced with the importation of ornamental fishes from Asia has been reported parasitizing poecilids. This is the second reference to the parasite in Brazil and the first report of pathological findings related to this nematode species (Alves et al, 2000;Menezes et al, 2006). Piazza et al (2006) have reported camallanid nematodes in low prevalence in commercialized X. maculatus and Poecilia sphenops from Southern Brazil.…”