Effects Of Fish Density On Spread Of Infectious Hematopoietic Necrosis Virus (IHNV) In Rainbow Trout, Oncorhynchus Mykiss

Abstract

Rainbow trout (Oncorhynchus mykiss) were held at one of seven densities (8, 4, 0.63, 0.31, 0.16, 0.08 or 0.012 fish per liter) and challenged to the infectious hematopoietic necrosis virus (IHNV) by cohabitation with a single presumably infected donor fish. The trout were exposed to the IHNV-infected fish for 11 days to determine the effect of density on occurrence, spread and prevalence of the disease. The host density and IHNV prevalence were positively associated (r2 = 0.89, regression analysis) with no occurrence of the virus at the two lowest densities (0.08 and 0.012 fish/l). Host density, therefore, is a key factor in determining the incidence and magnitude of IHNV infection.