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A Disease of Freshwater Fishes Caused by Tetrahymena Corlissi Thompson, 1955, and a Key for Identification of Holotrich Ciliates of Freshwater Fishes

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A Disease of Freshwater Fishes Caused by Tetrahymena Corlissi Thompson, 1955, and a Key for Identification of Holotrich Ciliates of Freshwater Fishes University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln US Fish & Wildlife Publications US Fish & Wildlife Service 1975 A Disease of Freshwater Fishes Caused by Tetrahymena corlissi Thompson, 1955, and a Key for Identification of Holotrich Ciliates of Freshwater Fishes Glenn L. Hoffman US Fish and Wildlife Service M. Lando National Zoological Park, Washington, D.C. J. E. Camper National Fish Hatchery D. W. Coats University of Marylan J. L. Stookey U. S. Army Medical Research Institute of Infectious Diseases See next page for additional authors Follow this and additional works at: https://digitalcommons.unl.edu/usfwspubs Part of the Aquaculture and Fisheries Commons Hoffman, Glenn L.; Lando, M.; Camper, J. E.; Coats, D. W.; Stookey, J. L.; and Burek, J. D., "A Disease of Freshwater Fishes Caused by Tetrahymena corlissi Thompson, 1955, and a Key for Identification of Holotrich Ciliates of Freshwater Fishes" (1975). US Fish & Wildlife Publications. 112. https://digitalcommons.unl.edu/usfwspubs/112 This Article is brought to you for free and open access by the US Fish & Wildlife Service at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in US Fish & Wildlife Publications by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Authors Glenn L. Hoffman, M. Lando, J. E. Camper, D. W. Coats, J. L. Stookey, and J. D. Burek This article is available at DigitalCommons@University of Nebraska - Lincoln: https://digitalcommons.unl.edu/ usfwspubs/112 THE JOURNAL OF PARASITOLOGY Vol. 61, No. 2, April 1975, p. 217-223 A DISEASEOF FRESHWATERFISHES CAUSED BY TETRAHYMENA CORLISSITHOMPSON, 1955, AND A KEYFOR IDENTIFICATION OF HOLOTRICHCILIATES OF FRESHWATERFISHES G. L. Hoffman,* M. Landolt,t J. E. Camper,$ D. W. Coats,? J. L. Stookey,I and J. D. Burekf ABSTRACT: Tetrahymenacorlissi, a free-living protozoan, apparently caused the death of large numbers of guppies (Poecilia reticulatus) and occasionally other fishes, in aquaria and hatcheries at several locations. Apparentlythe disease occurs when the fish and protozoan populations are both at a high level of density. The signs include white spots and epidermal damage. Histologically, T. corlissi could be seen in skin, mus- cle, and viscera; in some there was marked inflammation,in others there was little tissue reaction. A key is presented for the identification of invasive fish ciliates: Chilodonella, Hemiophrys, Ichthyophthirius, Ophryoglena,and Tetrahymena. Eight times during the past 3 years we have Ophryoglena sp., while being kept in small diagnosed a disease caused by a facultative aerated aquaria for other purposes. In extreme parasitic ciliate of the genus Tetrahymena. cases the epithelium becomes so necrotic, due Most cases involved aquarium fishes-guppies to the invading protozoa, that it sloughs in (Poecilia reticulatus) 6 times, and an uniden- patches and the fish die. Migala and Kazubski tified aquarium fish once. One case of Tetra- (1971, 1972) reported epizootics caused by hymena sp. disease in catfish (Ictalurus punc- free-living ciliates (Chilodonella cucullus, C. tatus) was found by F. Meyer in Arkansas uncinata, Dexiostoma campylum, Glaucoma (pers. comm.) and verified by one of us (G. scintillans, Colpidium colpoda, Frontonia acum- L. Hoffman). It is probable that any species inata, F. leucas) on carp following overwin- of freshwater fish can be affected. The diseased tering in Polish ponds. Similarly, Purdom and fish came from Arkansas, Maryland, Michigan, Howard (1971) described epizootics in fish North Carolina, Tennessee, West Virginia, and reared in marine fish hatcheries, caused by California. This protozoan is common in nature facultative parasitic ciliates of the species Heli- and probably has no geographical limits in costoma buddenbrooki. However, in contrast North America. A similar Tetrahymena has to all aforementioned ciliates, Tetrahymena has been reported from Europe (Ergens and Lom, been found repeatedly and its pathogenic action 1970). has been clearly established by repeated ob- Some reports indicate that invasions of fishes servations and histological proof. Experimental by free-living ciliates of various genera may infection, however, has not been achieved. be frequent. A new fish disease was reported Beginning with Epstein's report in 1926, by Hoffman (1967) when experimental fishes Tetrahymena has been reported from fishes, (largemouth black bass, bluegill, fallfish, creek amphibians, baby chicks, and possibly from chub, sculpin) were killed by the protozoan, man. Further detail was given in reviews by Corliss (1960, 1970). Received for 3 1974. publication July The ciliate studied us was T. corlissi. * Eastern Fish Disease Laboratory, U. S. Bureau by It is the of this to: of Sport Fisheries and Wildlife, Kearneysville, purpose paper (1) describe WV 25430. Present address: U. S. Fish Farming it because the description by Thompson (1955) Experimental Station, Stuttgart, AR 72160. was in abstract only, (2) present a scheme for of t Department Pathology, National Zoological differential diagnosis of holotrichs of fishes, Park,Washington, D.C. 20009. and (3) describe the histopathologic changes t National Fish Hatchery, P.O. Box 158, Pisgah in host tissues after are invaded Forest, NC 28768. they by the ? Zoology Department, University of Maryland, organism. College Park, MD 20742. IIU. S. Army Medical Research Institute of In- Tetrahymena corlissi Thompson, 1955 fectious Diseases, Fort Detrick, Frederick, MD (Figs. 1-4) 21701. TfPathology Department, Johns Hopkins School of The ciliate isolated from guppies in Cali- Medicine, Baltimore,MD 21205. foria which was studied by Jiri Lom (pers. 217 218 THE JOURNAL OF PARASITOLOGY,VOL. 61, NO. 2, APRIL1975 Ui r\ t 4 ) HOFFMAN ET AL.-TETRAHYMENACORLISSI, A PATHOGENOF FRESHWATERFISHES 219 comm.) is typical T. corlissi. In material from 2a. Body flat, dorsoventrallycompressed ..--. ------------- Chilodonella other areas, minor variation was noted in 2b. round in treated with the silver stain of Chat- Body transversesection 3 specimens 3a. Population consisting of individuals of con- ton-Lwoff (Corliss, 1953b). Most probably, spicuously different sizes (from 40 um to however, they are variants of T. corlissi. about 1,000 Lm), larger specimens have a horseshoe-shapedmacronucleus -. Description .._.----_---------------..... .--.. .--- --- Ichthyophthirius Body ovate; anterior end pointed, posterior 3b. Population consisting of individuals of about rounded, 53 (30 to 70) tumlong by 20 to 45 /Lm equal size ---------- .------ 4 wide. Uniformly covered by cilia arranged in 27 4a. About 150 to 200 ,um by 85 ,m; ellipsoid; (23 to 29) meridional rows; 1 or 2 rows reaching macronucleus elongated; buccal apparatus only to posterior border of buccal apparatus, the with a depression in form of the number "6", rest reach anterior pole or suture above buccal a refractile "watch-glass" structure in cyto- apparatus (Figs. 2, 4). This arrangement differs plasm close to the side of the buccal ap- from that described by Thompson (1955) who paratus. About 85 meridional ciliary rows, stated that T. corlissi has 2 postoral rows. Buccal of which 9 are postoral. No caudal cilium apparatus with an undulating membrane of coales- ............... ........ ... Ophryoglena cent cilia (to the observer's left) and with 3 4b. About 30 by 50 utm;ovate to pear-shaped, obliquely set membranelles, each 3 ciliary rows with anteriorend more or less pointed; macro- wide (to the right). Buccal apparatusnear anterior nucleus round to oval; buccal apparatussmall, pole of body (Figs. 3, 4). An 11- by 9-,am oval drop-shaped, close to anterior end. From 25 to round macronucleus lies near a 2- to 3-,um to 31 meridional ciliary rows, of which 1 micronucleus. or 2 are postoral. A single caudal cilium _.... .----.------.-.. -... ............. Tetrahymena corlissi Differential diagnosis associated with T. corlissi Although the ciliate can be seen under a dis- Pathology secting microscope, generic diagnosis can be made Grossly the infection is often seen as small only by observing the ciliate in wet mounts or (1 mm) white spots in the skin and musculature sections. To determine the histological species, of the fish, accompanied by extensive impregnation methods (such as Chatton-Lwoff, sloughing of the elevation of the and Klein's, or Bodian's protargol), which reveal the epidermis, scales, a "silver line system" of ciliary rows, are necessary. loss of equilibrium. The white spots are The finding of small ciliates in the tissues of areas of necrosis which contain the ciliate. In North American fishes indicates infection by at the cases studied female fish died within 1 of least one the following: Tetrahymena corlissi, week after infection, and males in 1 to 3 weeks. Ophryoglena, Hemiophrys, juvenile Ichthyoph- The protozoans were seen on thirius, or possibly Chilodonella. Because of recent readily living confusion in the identification of some of these- fishes with a dissecting microscope and could particularly Tetrahymena,Ophryoglena, and Hemi- be demonstrated easily in wet mounts (Fig. ophrys-we present here the comparative features 1). Many parasites were seen in the blood and a dichotomous (Table I) key. vessels of the gills of one dead guppy. Key to holotrich ciliates of freshwater fishes Histologically, the protozoan could be seen superficially in the skin and in the musculature (does not include species described as rare facul- of the tative parasites by Migala and Kazubski,
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