We have read with interest the scientific paper published in PLoS One journal claiming that goldfish pose a risk to frogs in garden ponds because of ranavirosis.
However, we do not believe the evidence in that paper is strong enough to draw that conclusion so people should not be tempted to get rid of goldfish from their ponds or stop stocking them in the future.
The RANA project, which ran for more than 3 years in 2005 looking at this very issue, concluded in its final report: “There was no evidence of ranavirus infections in imported consignments of ornamental fish suggesting there is very little, if any, risk of introducing exotic pathogenic ranaviruses from third-countries via the import trade in ornamental fish.”
And the 2011 paper Common Carp and goldfish were not susceptible to challenge with ranavirus under certain challenge conditions (Jensen et al) also found that imported goldfish could not transmit the virus: “We conclude that carp and goldfish are not susceptible to ranavirus under the experimental conditions applied and are unlikely to become carriers of an infection.”
If people buy fish from reputable retailers (you can find a list of OATA retailers here who sign up to our Code of Conduct), dispose of pond plants carefully and don’t move goldfish from pond to pond we believe goldfish and wildlife can live side by side quite happily in British garden ponds.
After all, this was also the conclusion from the Freshwater Habitats Trust following its 2013 Big Pond Dip survey.
“Fish did not have a big impact on the range of invertebrate creatures present and, surprisingly, frogs were reported breeding slightly more often in fish ponds than in fishless ponds, and toads twice as often (because toad tadpoles are unpalatable to fish).
“However – and it’s an important ‘however’ – the survey doesn’t tell us anything about how many young amphibians emerge from garden ponds with fish: for frogs and newts its likely to be a lot less than in fishless ponds.”