Hundreds of dead fish filled a canal despite an emergency rescue mission as men worked through the night to save as many stricken animals as possible. 

Dying fish could be seen gasping near the surface of the Worcester and Birmingham Canal near Blockhouse Lock in Worcester this afternoon.

Worcester News: SAD: Dead fish in the Worcester and Birmingham Canal in Worcester SAD: Dead fish in the Worcester and Birmingham Canal in Worcester (Image: James Connell/Newsquest)

Meanwhile, large numbers of dead fish - some witnesses estimated hundreds - lay strewn in the stagnant water.  The bulk of the carcasses had collected near the entrance to the lock by the city's Lock Street, some already picked over by gulls. 

The fish died because of falling oxygen levels in the canal near Blockhouse Lock, by Lock Street, due to soaring temperatures and thunderstorms.

We were told by men operating the pumps for the Canal and River Trust that, because of the heat and humidity, oxygen levels in the canal were reduced.

READ: Live - hundreds of dead fish in city canal 

READ MORE: Thunderstorm weather warning upgraded to amber 

James Kirk of MEM Fisheries (a contractor for the Trust) and a colleague quickly set up two pumps to get water with a higher oxygen content back into the canal in the hope it could revive some of the fish still struggling.

Worcester News: QUICK: James Kirk of MEM Fisheries sets up the air pump which will increase oxygen levels as he is caught in a race against time to save as many fish as he can QUICK: James Kirk of MEM Fisheries sets up the air pump which will increase oxygen levels as he is caught in a race against time to save as many fish as he can (Image: James Connell/Newsquest)

He said some of the fish in difficulty would survive thanks to the spray bar he had developed for this purpose. "This is happening all over the country. With the temperatures we have been having, the water is struggling to hold the oxygen levels," he said.

The issue has been exacerbated by thunderstorms which have created urban run-off, further lowering the oxygen content of the canal by washing 'dirty, low oxygen water' into the course. Similar problems have also been reported in Stourport, he said.

Worcester News: VITAL: One of the pumps set up by MEM Fisheries to increase oxygen levels in the canal and save the struggling fish after heat and thunderstorms made the water perilous for fish VITAL: One of the pumps set up by MEM Fisheries to increase oxygen levels in the canal and save the struggling fish after heat and thunderstorms made the water perilous for fish (Image: James Connell/Newsquest)

Mr Kirk and a colleague even set up tents by the canal to work overnight to save the fish. "We have had a busy day - and we will be staying out all night to do this," he said.

This was despite an amber weather warning, issued by the Met Office, for thunderstorms including hail, heavy rain and strong winds.

Chris Watson who lives at Lock Cottage by Blockhouse Lock said he learned about what had happened from the postman and then had a look himself.

He said: “It’s tragic. I got on the phone straight away to the Canal and River Trust. I’ve lived here two years. It’s really sad. People fish in this area.”

Diane King of Spring Lane, which overlooks the canal, said: “I have seen lots of dead fish floating past. You can see pollution in the water. It looks like petrol.

“It’s not nice to see the dead animals. People go past on barges. I don’t know if the water is dangerous to humans. It’s quite nasty. Environmental Health has been told about it.”

The contractors who work on behalf of the Canal and River Trust were set to be at the canal all night trying to resolve the issue and were setting up tents for shelter with an amber weather warning in force as the Worcester News went to press.