Biodiversity of Metazoan Parasites Infecting Channel Catfish (Ictalurus punctatus), Blue Catfish (Ictalurus furcatus), and C×B Hybrid Catfish (Female Ictalurus punctatus × Male Ictalurus furcatus) in Earthen Pond Aquaculture

Abstract

This 1-year in-pond study documents the metazoan parasite biodiversity in channel catfish (Ictalurus punctatus), blue catfish (Ictalurus furcatus), and C×B hybrid catfish (female Ictalurus punctatus × male Ictalurus furcatus) in earthen pond aquaculture. A total of 750 individuals per fish species were stocked into 3, 0.1-arce earthen ponds (each pond comprising a replicate). A total of 112 (mean of 3 per month per pond) channel catfish, 74 (mean of 2 per month per pond) blue catfish, and 209 (mean of 6 per month per pond) C×B hybrid catfish were seined and examined by routine parasitological necropsy using light microscopy during January, February, April, May, June, July, September, October, November 2010, and January, February 2011, totaling 11 collection events. All parasites were observed alive before being heat-killed, fixed in 10% neutral buffered formalin, 70% EtOH, 95% EtOH, or glacial acetic acid, and identified to the lowest taxonomic level using the published literature and previously-collected specimens. Based on morphological criteria, specimens comprising a total of 15 metazoan parasite species were collected from these catfishes. Channel catfish was infected by14 species: 4 myxozoans Henneguya cf. postexilis, H. cf. exilis, H. cf. adiposa, and H. cf. ictaluri (combined prevalence of 81.3%), 2 monogeneans Ligictaluridus mirabilis and L. pricei (99.1%), 5 cestodes Corallobothrium fimbriatum, C. parafimbriatum, Corallotaenia intermedia, Megathylacoides cf. giganteum, and M. thompsoni (57.1%), 1 nematode Spiroxys cf. contortus (0.9%), and 2 copepods Neoergasilus japonicus and Achtheres cf. percarum/ sandrae (16.1%). C×B hybrid catfish was infected by 12 species: 3 myxozoans Henneguya cf. postexilis, H. cf. exilis, and H. cf. adiposa (36.4%), 2 monogeneans Ligictaluridus mirabilis and L. pricei (90.4%), 3 cestodes Corallobothrium fimbriatum, C. parafimbriatum, Corallotaenia intermedia (47.8%), 1 nematode Spiroxys cf. contortus (0.5%), 1 unionid Pyganodon cf. grandis (2.9%), and 2 copepods Neoergasilus japonicus and Achtheres cf. percarum/ sandrae (6.7%). Blue catfish was infected by 7 species, 2 myxozoans Henneguya cf. postexilis and H. cf. ictaluri (9.5%), 2 monogeneans Ligictaluridus mirabilis and L. pricei (93.2%), 2 cestodes Corallobothrium fimbriatum and C. parafimbriatum (35.1%), and 1 copepod Neoergasilus japonicus (21.6%). Although hybrid catfish resistance to disease has yet to be tested for most parasite infections, these results clearly show that this hybrid is no refractory to initial infection by the parasites that infect its parental species. New host records reported herein comprise Henneguya postexilis in C×B hybrid catfish and blue catfish, H. exilis in C×B hybrid catfish, H. adiposa C×B hybrid catfish, Ligictaluridus mirabilis in C×B hybrid catfish, L. pricei infected C×B hybrid catfish, Corallobothrium fimbriatum in blue catfish and C×B hybrid catfish, C. parafimbriatum in channel catfish, blue catfish and C×B hybrid catfish, Corallotaenia intermedia in channel catfish and C×B hybrid catfish, Spiroxys cf. contortus in channel catfish and C×B hybrid catfish, Pyganodon cf. grandis in blue catfish and C×B hybrid catfish, Neoergasilus japonicus in C×B hybrid catfish, and Achtheres cf. percarum/sandrae in channel catfish and C×B hybrid catfish.