The following toxicity signs from excessive vitamin A have been reported:
Rainbow trout (Oncorhynchus mykiss): Reduced growth and hematocrit; severe necrosis and (or) erosion of anal, caudal, pelvic and pectoral fins; scoliosis; lordosis; vertebral lesion; hemorrhages; increased mortality; pale yellow livers (McLaren et al., 1947; Primbs et al., 1971; Hilton, 1983).
Vitamin A fed to rainbow trout at the levels of 900,000 or 124,000 IU per kg diet did not seem to be toxic (Hilton et al., 1978a; Hilton, 1983), whereas levels of about 2.7 million IU were toxic (Hilton, 1983).
Brown trout (Salmo trutta L.): 100,000 IU per kg was found not to have any effect on growth or epidermal thickness and goblet cell concentration (Pickering, 1978).
Brook trout (Salvelinus fontinalis): Reduced growth, hematocrits; necrosis and hemorrhage of the skin, particularly at the base of the fins (Poston et al., 1966; Poston, 1971a); toxic level of vitamin A, 2.2 million IU per kg diet.
Atlantic salmon (Salmo salar): No effect on growth but increased mortality at 122,500 IU per kg (Grisdale-Helland et al., 1991).
Turbot (Psetta maxima): High incidence of skeletal deformities in larvae (Estévez and Kanazawa, 1995).
Japanese flounder (Paralichthys olivaceus): Reduced growth, larval skeletal deformity, including abnormal bone formation of the caudal fin, in larvae fed Artemia nauplii enriched with 100,000 IU vitamin A in a 10-L medium (Dedi et al., 1995, 1997; Takeuchi et al., 1995, 1998).
Tilapia (Oreochromis niloticus): Impaired skeletal and in particular vertebra formation; skin hemorrhage, necrosis of the caudal fin, enlargement of the liver and spleen; metabolic disturbances commencing at levels of 10,000 IU vitamin A per kg, and toxicity signs evident at 40,000 IU per kg (Saleh et al., 1995).
