Histopathological Effects of Trichodiniasis in Farmed Freshwater Rainbow trout, Oncorhynchus mykiss in West of Iran

The aim of present study was to monitor the presence
of Trichodina sp. in Rainbow trout, Oncorhynchus mykiss collected
from various fish farms in the western provinces of Iran during
January, 2013- January, 2014. Out of 675 sampled fish 335, (49.16%)
were infested with Trichodina. The highest prevalence was observed
in the spring and winter followed by autumn and summer. In general,
the intensity of infection was low except in cases where outbreaks of
Trichodiniasis endangered the survival of fish in some ponds. In light
infestation Trichodina is usually present on gills, fins and skin of
apparently healthy fish. Clinical signs of Trichodiniasis only appear
on fish with heavy infections and cases of moderate ones that are
usually exposed to one or more stress factors including, rough
handling during transportation from ponds, overcrowdness,
malnutrition, high of free ammonia and low of oxygen concentration.
Clinical signs of Trichodiniasis in sampled fish were sluggish
movement, loss of appetite, black coloration, necrosis and ulcer on
different parts of the body, detached scales and excessive
accumulation of mucous in gill pouches. The most obvious
histopathological changes in diseased fish were sloughing of the
epidermal layer, aggregation of leucocytes and melanine-carrying
cells (between the dermis and hypodermis) and proliferative changes
including hyperplasia and hypertrophy of the epithelial lining cells of
gill filaments which resulted in fusion of secondary lamellae. Control
of Trichodiniasis, has been achieved by formalin bath treatment at a
concentration of 250 ppm for one hour.

• Z. Khoshnood
• R. Khoshnood

• Gill
• Histopathology
• Rainbow trout
• Trichodina.

[1] C.V.F. Dujin, Diseases of Fishes. 3rd Ed., I, Life Books, London. 1973, pp. 486.
[2] B. Kugel, R.W. Hoffman, A. Fries, Effect of low pH on the chorion of rainbow trout and Brown trout. Journal of Fish Biology, 1990, 37: 301-310.
[3] T.L. Wellborn, Trichodina of freshwater fishes of the south eastern U.S. Journal of Protozoology, 1967, 14(3): 399-412.
[4] G.L. Hoffman, Ciliates of freshwater fishes. In: Parasitic Protozoa, London, Academic Press, 1978, 11: 632-983.
[5] E. Amlacher, Text Book of Fish Diseases. T.F.S. Publication, Jersey, USA, 1970, pp. 117-135.
[6] K. Molnar, Protozoan diseases of the fry herbivorous fishes. Acta. Vet. Aca. Scientiarum Hungarica, Tomus, 1971, 21(1): 1-14.
[7] C.R. Kennedy, A checklist of British and Irish freshwater fish parasites with note on their distribution. Journal of Fish Biology 1974, 6: 613-644.
[8] J.G. Van As, L. Basson, Checklist of freshwater fish parasites from southern Africa, S.A. rydskr. Natucirnav., 1983, 14(2): 49-61.
[9] R.R. Kudo, Protozoology. 5th ed. Thomas, Springfield, Illinois, U.S.A., 1966, pp. 164-177.
[10] A.T.A. Ahmed, Trichodiniasis of gold fish and other carps. Bangladesh Journal of Zoology, 1976, 4(1): 12-20.
[11] I. Paperna, J.P. Thurston, Report on ectoparasite infections of fresh water fish in Africa. Bull. Off. Int. Epiz., 1968, 69(7-8): 1197-1206.
[12] J.F. McArdle, Trichodina as cause of mortalities in cage reared Rainbow trout and Salmon. Bull. Eurp. Ass. Fish. Pathol., 1984, 4: 3-6.
[13] M.E. Eisa, S.O. El-Shazly, M.H. Rizk, A Contribution to the pathological changes of ectoparasite trichodinids-affected salt water fish (Grey Mullet fingerlings) in Raswa fish farm. J. Egypt. Vet.Med. 1985, 45: 107-113.
[14] R.H. Klinke, Fish Pathology. T.F.H. Publications, 1973, p. 217.
[15] Z. Lucky, Method for the Diagnosis of Fish Diseases. Amerind Publishing Co., New Delhi. 1977, pp. 203-218.
[16] R. Mortoja, M. Mortoja–Pierson, Initiation Aux Techniques de l histologe animale. Masson et Cie, Paris, 1967, p. 345. (In French)
[17] Z. Khoshnood, A. Mokhlesi, R. Khoshnood, Bioaccumulation of some heavy metals and histopathological alterations in liver of Euryglossa orientalis and Psettodes erumei along North Coast of the Persian Gulf. African Journal of Biotechnology, 2010, 9(41): 6966-6972.
[18] R.J. Roberts, Fish Pathology, Bailliere Tindall. London. 1978, pp. 563-570.
[19] H. Ogut, A. Akyol, Prevalence and Intensity of Ectoparasites in Rainbow Trout (Oncorhynchus mykiss) from Larvae Stage to Market Size in Turkey. The Israeli Journal of Aquaculture – Bamidgeh 2007, 59(1), 23-31.
[20] S.F. Snieszko, R. Axelrod, Diseases of Fishes. T.F.H. Publications, Inc., Ltd. 1971, p. 481.
[21] S.A.D. Abu El-Wafa, Protozoa parasites of some fresh water fishes in Behera Governorates. M.V. Sc. Thesis, Alexandria University. 1988, pp. 112-115.
[22] N.R.H. El-Khatib, Some studies on ectoparasitic infestation in fresh water fishes. M.V. Thesis, Cairo University. 1989, pp. 81-83.
[23] M.A. Abdel Meguid, Parasitological and histopathological studies on the grass carp. M.V. Sc. Thesis, Ain Shams University. 1989, pp. 117-120.
[24] E.E. Brown, J.B. Gratzek, () Fish Farming Handbook, A.V.I. Publication, Inc., Westport, 1980, pp. 287-289.
[25] M.A.H. Hassan, () Studies on some parasitic affections in fresh water fishes in Beni-Suef Governorate.P.D.V.Sc. Thesis, Cairo University. 1992, pp. 85-89.
[26] W.A. Rogers, J.L. Jun, Lesions of protozoan diseases in fish. In: the Pathology of Fishes, ed. 1975, pp. 201-212.