Transmission of Walleye Dermal Sarcoma and Lymphocystis via Waterborne Exposure

A study was conducted to determine if walleye dermal sarcoma could be experimentally transmitted by waterborne exposure of tumor-free walleyes Stizostedion vitreum to tumor-positive walleyes by cohabitation. Uninfected walleyes were placed in a common raceway with tumor-positive fish for either 5 or 15 d. Direct contact between the two groups of fish was prevented by two screen barriers. The exposed fish were then maintained in the laboratory for a total of 20 weeks. Walleye dermal sarcoma developed in 89% and 71% of the fish exposed for 5 and 15 d, respectively. There was no significant difference (P > 0.05) in incidence of tumors between the two groups of fish exposed for different lengths of time.