Fishermen are urgently appealing for help pumping air into lakes to the south of Chichester where thousands of fish have died.
The prolonged dry weather has led to a severe drop in oxygen levels in Ivy Lake and Triangle Lake, with the shallow water now also at risk from overheating.
A team of anglers and park volunteers have been working flat out to clear the stinking dead fish over the last few days with fears growing for the other lakes in the area.
Ralph Baker, who works at Park Holidays UK, said the loss of the small fry and larger specimen fish was ‘heartbreaking’.
He said: “It is a devastating and upsetting loss, quite heartbreaking really.
“The Environment Agency have lent us pumps and the local anglers are helping but the main task will be removing the dead fish.
“Anyone that can help is more than welcome to come down but I must stress it’s not for the faint-hearted and will be rather smelly.”
He added that the loss of oxygen levels was ‘not an uncommon problem’ in the hot weather and numerous fisheries across the UK were having similar issues.
Fisherman Ian Pedwell, 58, has been fishing at the lakes since 1972 and said he had never seen anything like it.
He said: “A lot of the big fish I’ve watched grow up from little fish, it’s soul destroying, it really is.”
The group urgently need pumps to prevent further issues and those able to help are encouraged to bring equipment to the lakes.
North Mundham Parish Council has asked for anyone with a diesel water pump or a jet ski to help oxygenate the water to call the water bailiff on 07770888701.
A spokesman for the Environment Agency said: “Our officers have provided advice to the owners of a private fishery at Ivy Lake in Chichester, after the hot weather caused the deaths of more than 1,000 fish over the weekend.
“Warm conditions can lead to low water flows, reducing oxygen levels, as temperatures increase in lakes and rivers.
“If anyone sees fish in distress, they should call our incident hotline: 0800 807060.”