Source(s):
Roy Yanong rpy@ifas.ufl.edu, 813-671-5230 ext. 104
Riccardo Russo rrusso@ifas.ufl.edu, 813-671-5230
RUSKIN, Fla.—Fear of needles will not be a problem for tropical fish receiving a new vaccine being tested by University of Florida researchers.
Carefully injected into the body of fish, the vaccine will prevent and treat streptococcus infections in two popular species — the Rainbow Shark and the Redtail Black Shark.
“These fish are important for Florida’s ornamental tropical fish industry, which produces, by some estimates, 90 to 95 percent of the nation’s domestically raised tropical fish,” said Roy Yanong, an assistant professor of aquaculture with UF’s Institute of Food and Agricultural Sciences. “As with any disease, prevention and rapid cure will help reduce losses for producers and benefit consumers who purchase tropical fish for their aquariums.”
He said streptococcus infections are troublesome for many species of tropical fish. If environmental conditions such as water temperature and water quality are not right, and if the disease-causing strains of streptococcus are present, the fish can develop the disease and pass it to other fish in the population. The result often is a mortality rate between 50 percent and 70 percent for the infected fish, Yanong said.
Yanong, based at UF’s Tropical Aquaculture Laboratory in Ruskin, said previous treatment methods using medicated food and antibiotic baths have not been as effective because they do not address the problem until the fish are already sick. Antibiotics placed in the water are not absorbed well by fish and can also lead to bacteria resistance. Medicated feed does not work well because the fish often stop eating when they are sick.
“If the analyses continue to show good protection levels, we will encourage producers to start vaccinating their broodstock against Streptococcus iniae,” Yanong said.
Yanong said they are working on this particular strain of streptococcus, but they hope to develop vaccines for other diseases that affect tropical fish.
“By preventing this disease instead of treating it after it has occurred, producers can save thousands of dollars,” Yanong said. “In an industry that generated more than $43 million in farm-gate sales last year, these are important savings for producers.”
Riccardo Russo, a graduate student who is conducting experiments on the vaccine at the Ruskin laboratory, said tests on different vaccines and methods of delivery show that injection provides the best results in both juveniles and adult fish.
“We are getting a 60 to 70 percent survival rate for infected fish receiving the injection, compared to a mortality rate that could be as high as 100 percent for fish that do not receive the vaccine,” Russo said. “By placing the vaccine directly into the fish, we can make sure they are getting the protection they need.”
In addition to improving survival rates, the vaccine protects against streptococcus for at least eight months in tests, Russo said. This helps tropical fish producers save money by reducing treatments for the disease to once a year, compared to other antibiotic treatment regimens that do not last as long.
While the new injected vaccine will be very helpful for adult fish, especially broodstock, bath treatments and oral treatments may be more practical and feasible for use in younger fish, and these delivery methods are still under investigation, he said.
Development of the new vaccine is the result of a partnership between researchers at UF’s Ruskin laboratory and Novartis AquaHealth Inc., Bothell, Wash. The vaccine could be available to tropical fish producers in the near future, Russo said.
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