Efficacy of Vaccination Against Streptococcus iniae During Artificial Spawning of the Red-Tail Black Shark (Epalzeorhynchos bicolor, fam. Cyprinidae)

Abstract

Artificial spawning may precipitate high mortalities of red-tail black shark (Epalzeorhynchos bicolor) broodstock from Streptococcus iniae infection. Two vaccine formulations (aluminum or oil adjuvant) were evaluated for effectiveness. Fish (mean weight 21.2 ± 5.7 g) were harvested, acclimatized, and vaccinated by intracoelomic injection. After 21 days, fish were moved to a biosecure laboratory and, one day later, simultaneously spawned and challenged by bath or by intracoelomic injection with S. iniae. Both formulations increased relative% survival (RPS) in unspawned (RPS [formulation]: 80 [aluminum]; 54 [oil]) and spawned fish (87–95 [aluminum]; 73–75 [oil]), suggesting that vaccination increases survival of red-tail black shark broodstock after spawning.

KEYWORDS:

• Streptococcus iniae
• cyprinid
• red-tail black shark
• vaccine
• spawning
• ornamental fish

This research was funded by a grant from USDA-CSREES. We want to thank Dr. Richard Miles and Dr. Jack Gaskin from University of Florida for their advice and support, and Dr. Joyce Evans and Dr. David Pasnik (USDA, ARS, Aquatic Animal Health Research Laboratory) for critical reading and helpful suggestions on the manuscript. Special thanks go to the Florida Tropical Fish Farms Association for its support, and to Craig Watson, Scott Graves, Robert Leonard, Sherry DeMayo, and Tina Crosby for assistance with fieldwork and in the laboratory.