Bull. Eur. Ass. FishPathol. J (l), 14, 1985

DIPLOSTOMATOSISIN CULTURED VENEZUELAN GREY MULLETS By G. CoNnoy, D.A. CoNRoY, J.A. SaNr,q'cANAAND F' PEnoouo

The Venezuelan authorities have 4009) was obtained from one of the assigned a top priority rating to the ponds. It was noted that I of the culture of an edible native characin lebranche mullets had a single metacer- known as "cachama" (Colossoma cariae in each eye. In addition, this silver mqcrompomrz.iCuv., l8l8), lebranche had bilateral cataract. No mullet ( liza Yal., 1836) and silver metacercariaewere detected in a random mullet (M. curema Val., 1836) respec- sample of 7 "cachamas" taken from the tively. In 1982a private concern initiated samepond. the mixed culture of these 3 speciesat One of the affected silver mullet eyes Boca de Aroa, Falcon State, in an earth was fixed in 1090 buffered formol saline pond complexwith a total surfacearea of for histological studies, . and living 22.5 Ha situated approximately l0 km metacercariae were removed from the from the coast. Small juvenile mullets other eye and fixed in cold acetic acid- were captured during February 1983 in formalin prior to staining in Delafield's watersof varying saiinity at the mouth of haematoxylin. On a basis of its the River Aroa, and were held for 7 days morphological characteristics and in a 1 : I mixture of fresh water and sea measurements,the parasite was identified water before being introduced together as the metacercaria of Diplostomum with "cachamas" to the ponds containing compactum (Lutz, 1928)Dubois, 1970in freshwater. The are fed a commerciai accordance with the detailed description pelleted feed, with supplementary food given by Ostrowski de Nirnez (1982) for beingderived from the fertilization of the this .In histological section, the water with chicken manure, until they affected eye showed epithelial vacuoli- attain a size suitable for sale to the zation and degeneration of the lens consumer. consistentwith a diagnosisof cataract. During routine samplng of the stock, The presence of metacercariae of the presenceof what was identified as Diplostomum compactum has been "eye t1uke" was detected in lebranche reported from native cichlids and mullet and silvermullet in the poads by introduced tilapias in Lake Valencia, the company's biologist in December Venezuela(Ostrowski de Nrinez, 1982; 1983.The problem was again observed Conroy, Gonz|lez & Gonzhlez, 1983). during January, Irebruary, March and Ostrowski de Nfnez (op. cit.) confirmed April 1984,and the authorswere invited that the first intermediate host of the to investigatethe occurrencein May 1984. trematode is the pulmonate snaii A randonr sample of 4 lebranchernullet Biomphalariuprona, and the final host is (length:48-61cm; weight: 800-10009) and the neotropical cormorant Phqlacrocorax I silver mullet (length: 38cm; weight: olivqceus. D. comPactum has been Bull.Eur. Ass. Fish parhol. J (1),15, l9g5

reported as an intestinal parasite of case of lebranche mullet, and adds silver cormorants from Colombia (Rietschel& mullet to the list of mugilid species Werding, 1978),Cuba (Dubois & Macko, susceptible to diplostomatosis when 1972) and Venezuela (Nasir & Diaz, cultured in fresh water environments. It 1972).In addition, Dubois &Macko (op. can be confirmed at this stage that no cil./ detected the samespecies of parasite diplostomatid metacercariae have been in the snowy egret (Egrettq thula) in detectedto date in post-larval, juvenile or Cuba. adult grey mullet species from natural The only previous report of populations in coastal waters corres- diplostomatosisin grey mullets is that by ponding to insular environments and to Castro ( 1980), who detected the Venezuelanmainland respectively. metacercariaeof what was identified as Summary "Diplostomulum sp.', in 5 specimensof The presence of metacercariae of Diplostomum lebranche mullet and 6 specimens of compactum (Lutz, 1928)Dubois, 1970 in the evesof cultu red y g parassi mullet (Mugil lncllls Hancock, lebranchenullet (M ug i t ti zo al., l 36t and silvermullet (Mugi! curemaVal., lg36) from 1830) held in fresh a fresh water ponds at the water fish farm in Venezuela is described. This Repel6n Fish Culture Station on the constitutes a new geographical record for Diplostomun Atlantic coast of Colombia. The sp. in lebranche mullet, and a new geographical and host incidence record in silver mullet. of infection in both speciesof Metacercariae of D. compactum were not detected grey mullets was 10090,and the intensity in adult specimens of ,,cachama,, (Colossoma of infection was I metacercaria/eye. mdcropomus Cuv., l8l8) maintained for culture purposes in the same earth ponds as the mullets. Metacercariaewere not detected in 25 specimensof "cachama" from that site, Acknowledgments The Of the 18 different speciesof aquatic authors wish to thank Dr. Saul Regeff and Lic. Margot Grillo (Aquafin birds, including piscivores, C. A., Caracas) for studiedin situ having brought this problem ro rheir arrention.and by Castro, adult Diplostomum sp. were alsogratefully acknowledge rhe interpretation of the encountered in l0/10 great histopathological changes made by Dr. Rafael egrets Infante, (Cosmerodius j of this Faculty. The present report forms a albus), /7 black-crowned contribution to studies on grey mullet diseasesand night herons (Nycticorax nycticorax) and parasites in Venezuelan waters financed by the National Council 4,/4 snowy egrets(Egretta thula), but not for Scientific and Technolosical Research (CONICIT) of the Governmenr in the 2 of specimens of cormorants Venezuela as Research project No Sl-1350 (Phalacrocorax olivaceus) which were (ResponsibleScientist: Prof. D.A. Conroy). examined. References No mention of diplostomatosis as a Castro, A. Estudio sobre el Diplostomum sp. (Tre_ problem affecting speciesof mugilids has matoda : Diplostomatidae) que parasita a los been made in the review of grey mullet ojos de la mojarra amarilla (petenia kraussii Steindachner) y a los ojos de peces diseases and parasites published otros en la by Estaci6n Piscicola de Repel6n. Secretaria de Paperna& Overstreet(1981). The present Agricultura y Fomento, Unidad T6cnica. Cali. report thereforeconfirms the occurrence Colombia. 1980.90 pp, Conroy, D.A., M.C. Gonzdlezand of this parasitosis grey M.D. Gonzdlez, in mullets from Preliminary studies on an eye fluke problem northern South America, extends the affecting tilapias and native cicklids from Lake Valencia, previouslyknown geographicalrange of Venezuela. International Conference on Tilapias in Aquaculture, Nazareth, Israel. the trematodeto include Venezuelain the 8-13May, i983. Bull. Eur. Ass. Fish Pathol. 5 (l), 16, 1985

Dubois, G. and J.K. Macko. Contr\bution d l'6tude Paperna, I. and R.M, Overstreel. Parasites and desStrigeata La Rue, 1926(Trematoda, Strigeida) diseasesof mullets (Mugilidae). 1N : "Aqua- cleCuba. Ann. Parasit. hum. comp. 1972.47 : culture of Grey Mullets" (Editor: O H. Oren). 5l--75. International Biological Programme 26, Cam- Nosir,P. and M.T. Dfaz. Avian flukes of Venezuela. bridgeUniversity Press, London. 1981.411-493' Riv. Parassit.1972. 33 : 245*276. Rietschel,G, and B. Werding. Trematodes of birds ()strowski de Nunez, M. Dle Entwicklungszyklen from northern Colr-rmbia.Z. Parasitenkd.1978' von Diplostomum (AustrodipLostomum) com- 57 : 5'l-82. pactum (Lutz, 1928) Dubois, 1970 und D. (A') mordax (Szidat und Nani, l95l) n. comb' in S0damerika.Zoo). Anz., Jena. 1982.208:393* 404.

Authors'address: de Venezuela' Seccion de lctiopatologia, Facultad de Ciencias Veterinarias, Universidad Central Apartado de Correo No 4563, MARACAY 2101, Edo' Aragua, Venezuela'