Antibodies for a deadly fish virus have been found in fish in seven rivers in the UK, raising fears that the disease is becoming more widespread.
According an Environment Agency report, Tench Rhabdovirus antibodies have been detected in seven rivers, including: the River Trent in Nottinghamshire; the River Teme in Worcestershire; the Ridd Nidd and the River Wharfe in Yorkshire; the Witham in Lincolnshire; the Douglas in Lancashire and the River Wye in Derbyshire.
Several other rivers have also been tested and have provided negative results, including the river adjacent to a fish farm where an outbreak of the virus occurred last year.
Tench Rhabdovirus, which is named after the fish the infection was first isolated from, also affects other freshwater fish including roach, grass carp, crucian carp, chub, bream and dace. However, it's believed that tench and bream are the most susceptible to infection.
The virus was first isolated in Germany in the 1970s and caused widespread fish kills in the tench and bream populations of the River Bann in Northern Ireland in the early 1980s.
In 1999, movements of coarse fish from the River Bann's catchment to fish farms in England led to the infection killing lots of bream and tench at five separate locations.
Last year the virus struck a fish farm in Calverton, Nottinghamshire.
Nigel Hewett, the Senior Fish Health Scientist with the Environment Agency said:
"We do not know how serious these latest findings are. They do suggest that the virus may be more widespread than originally thought, but, as it does not appear to have caused any fish mortalities in the wild since 1999, it may not prove a serious threat to fish populations."