Variable Development of Cataracts and Retinal Degeneration in Pollack (Pollachius virens) Maintained in Three Different Aquarium Settings
IAAAM Archive
Taylor L. Reynolds1; Salvatore Frasca, Jr.2; K. Spencer Russell2; Herbert E. Whiteley2; Sonia L. Mumford3
1Tufts University School of Veterinary Medicine, N. Grafton, MA; 2Department of Pathobiology and Veterinary Science, University of Connecticut, Storrs, CT; 3New England Aquarium, Central Wharf, Boston, MA


Reports of cataracts in captive fish are plentiful, particularly in trout and salmon. Formation of cataracts has been linked to nutritional deficiencies11,10,4,17, rapid growth rates2,3, genetic inheritance15, toxins8,9, infectious agents, osmotic stress, and excessive exposure to ultraviolet (UV) radiation5,6,16,19. Retinal degeneration, in contrast, has been documented infrequently and has been associated with genetically manipulated transgenic zebrafish7,12 and celestial goldfish13,14, and with diabetes mellitus in carp.18 Eight of 18 wild-caught juvenile Pollack (Pollachius virens) were placed on display in a brightly lit tank at the National Marine Fisheries Service (NMFS) Aquarium in Woods Hole, MA, and 10 were shipped to the New England Aquarium (NEA) in Boston, MA. Six of the 10 pollack received by NEA were relocated to a dimly lit display tank, whereas 4 were placed in a brightly lit, basin-like tank, in a Puffin display. Within 4 months, 5 of 6 pollack in the dimly lit tank developed cataracts diagnosed by ophthalmoscopic examination. Affected pollack grew increasingly unable to locate food, became emaciated, and were euthanized 5 months after diagnosis. No gross lesions were identified in the coelomic viscera at necropsy examination, and globes were immersion-fixed in Bouin's solution for routine paraffin embedding and histopathologic examination. Subcapsular, cortical cataracts were found in 4 of 5 pollack, and were bilateral in 3 and unilateral in 1 pollack. Marked to severe retinal degeneration and atrophy was evident in 5 of these 5 pollack, the most severe degeneration being central rather than peripheral. None of the other 12 pollack from the original cohort of 18 developed cataracts clinically evident by ophthalmoscopic examination ante-mortem. However, upon histologic examination, 4 of 5 pollack from the NMFS facility had mild, focal, subcapsular cataracts, 3 unilateral and 1 bilateral, and 1 had retinal degeneration comparable to that of the pollack from NEA. In comparison, no microscopic lenticular or retinal lesions were identified in 5 wild-caught, adult pollack acquired from Connecticut fisherman and examined in the manner previously described. To our knowledge, this is the first documentation of the combination of cataract and retinal degeneration in a species of the family Gadidae. Differences in environmental and husbandry factors exist between the two NEA tanks and the two aquaria to provide clues as to the causative agent(s). Current investigations into the etiology are focused on determining variations in UV light exposure and nutrition between the three aquarium settings.


The authors acknowledge Tania Taranovski, Brandon Schmidt, and volunteers of NEA for their care of pollack, for providing answers regarding the husbandry conditions, and for assisting in medical examinations, euthanasia and necropsies of affected fish. We are grateful to Kevin Dunn from the National Marine Fisheries Aquarium for donating 5 pollack for this study and for supplying answers as to the husbandry conditions at the NMFS.


1.  Barash H., H.A. Poston, and G.L. Rumsey. 1982. Differentiation of soluble proteins in cataracts caused by deficiencies of methionine, riboflavin, or zinc in diets fed to Atlantic Salmon, Salmo salar, Rainbow Trout, Salmo gairdneri, and Lake Trout, Salvelinus namaycush. Comell Veterinarian 72:361-371.

2.  Bijerkas E., et al. 1995. Cataracts in rapidly growing farm raised Atlantic Salmon (Salmo salar), Veterinary Quarterly 17:1.

3.  Bjerkas E., et al. 1996. Cataract development in Atlantic Salmon (Salmo salar L) in fresh water, Acta. Vet. Scand. 37:351-360.

4.  Cowey C.B., et al. 1992. Methionine intake in rainbow trout (Oncorhynchus mykiss), relationship to cataract formation and the metabolism of methionine, Journal of Nutrition 122:1154-1163.

5.  Cullen A.P., and C.A. Monteith-McMaster. 1992. Damage to the rainbow trout (Oncorhyncus mykiss) lens following an acute dose of UVB, Current Eye Research 12, 97-106.

6.  Cullen A.P., C.A. Monteith-McMaster, and J. G. Sivak. 1994. Lenticular changes in rainbow trout following chronic exposure to UV radiation, Current Eye Research 13:731-737.

7.  Daly, F.J. and J.H. Sandell. 2000. Inherited retinal degeneration and apoptosis in mutant Zebra fish, Anatomic Record 258:145-155.

8.  Dobson, P. and Schuurman, H.J. 1990. Possible causes of cataract in Atlantic Salmon (Salmo salar), Experimental Eye Research 50, 439-42.

9.  Fraser, P.J.G. Duncan, and J. Tomlinson. 1990. Nuvan and cataracts in Atlantic Salmon (Salmo salar), Experimental Eye Research 50, 443-447.

10. Hughes S.G., et al. 1981. Biomicroscope and histologic pathology of the eye in riboflavin deficient rainbow trout (Salmo gairdneri), Comell Veterinarian 71:269-279.

11. Ketola H.G. 1979. Influence of Dietary Zinc on Cataracts in Rainbow Trout (Salmo gairdneri.) Journal of Nutrition. 109:965-969.

12. Malicki, J., et al. 1996. Mutations affecting development of the zebra fish retina, Development 123: 263-273.

13. Matsumura, M, et al. 1981. Electron microscopic studies on celestial goldfish retina- a possible new type of retinal degeneration in experimental animals, Experimental Eye Research 32, 649-656.

14. Matsumura, M., et al. 1982. Retinal degeneration in celestial goldfish, Ophthalmic. Research 14:344-353.

15. Noga, E.J., E.D. Wolf, and P.T. Cardeilhac 1981. Cataracts in Cichlid Fish, JAVMA 179:11:1181-1182.

16. Pitts, D,G., A.P. Cullen, and P.D. Hacker. 1977. Ocular effects of near ultraviolet radiation: Literature Review, American Journal of Optometry & Physiological Optics 54"8"542-549.

17. Richardson, N.L., et al. 1985. Influence of dietary calcium, phosphorus, zinc and sodium phytate level on cataract incidence, growth and histopathology in juvenile Chinook Salmon (Oncorhynchus tshawytscha), Journal of Nutrition 115:553-567.

18. Yokote, M. 1974. Spontaneous diabetes in carp (Cyprinus carpio) Special Publications Japan Sea Fish Lab 67-74.

19. Zigman S., J. Schultz and T. Yulo. 1973. Possible roles of near UV light in the cataractous process, Experimental Eye Research 15, 201-208.

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Taylor L. Reynolds

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