The Environment Agency has conducted tests on the water in Caerphilly Castle moat after the deaths of more than 70 carp.
Visitors to the 13th Century castle have reported spotting dead fish floating on the surface of the water which has prompted Environment Agency Wales to investigate.
A spokeswoman from Environment Agency Wales said: “We have had reports of more than 70 carp deaths at Caerphilly Moat since April 2012.
“We have taken water samples from the moat, but these haven’t shown anything that would have an impact on fish.
“We believe that the warm winter, coupled with the recent hot weather, has increased stress on the carp and led to the deaths.
“We are now working with Caerphilly and District Angling Association to improve habitat at the moat, which should help reduce stress on the fish population and help stop the problem recurring.”
More dead fish floating in the moat again this morning, and, this is after a very prolonged rainy period in which the moat is cleaned thoroughly.
Whatever is causing the problem it does not appear to be a natural event as has been suggest by the environment agency.
There is still a problem with a large fallen tree in the feeder to the moat, which has been there for some weeks now, the residents of the town who have complained about this have been told that it is a responsibilty of the Borough council who appear to be reticent to do very much about it????