Around half of the 70 fish from the prized Leney blood line at the Isle Estate pool near Shrewsbury have so far perished along with other wildlife.
Now volunteers have set up a special pumping system at the 12-acre lake at Bicton in a bid to create zones to help the fish, some of which weigh up to 40lbs, to breathe safely.
The affected pool is near the River Severn and in normal circumstances plays a part in holding rain water to prevent flooding in the area.
Due to heavy rainfall earlier this year, the water has overflowed into nearby woodland which has then rescinded and pushed debris back into the pool which has hit the oxygen flow.
The Isle lake is a popular coarse fishing haunt for members of the Prince Albert Fishing Society, Europe's largest angling club.
Shrewsbury member Will Bruce, 27, has set up camp at the site for 18 nights in a row to keep the pumps running with the help of other volunteers and the estate's owners.
"About three weeks ago I was down at the lake and noticed that the nature activity wasn't looking right. There was a massive algae bund. The fish and the insects were behaving strangely. The fish seemed to be coming to the surface and gasping for air.
"The algae had been really thriving on the nutrients flowing back into the pool. Then due to the recent hot weather and a lack of much rain the algae has used up pretty much all the oxygen.
"We started to monitor what was happening and installed the pumps.
"Then literally overnight the algae changed colour and died off. A lot of the insects and larvae also died and were floating on the surface. We lost about 32 fish which is roughly half of the stock here. Isle is a low stock site and the fish is much sought after.
"We have a lost multiples of fishing weighing 20lbs each. It is a great shame and as it's a rare type of carp we are trying really hard no to lose any more.
"My dad Richard has been relieving me during the day and another member Jamie Collier has been taking turns at nights to keep the pumps in fuel," the freelance design engineer says.
"It's not the first time that there's been an oxygen crash here.
"In the late 1970s to early 1980s when the lake was shallower and had a lot more fish in it a similar thing happened. There used to be hundreds here. Then in 2010 it was a very cold winter and the lake freezed over for a number of weeks and by the time it thawed many had died," Mr Bruce added.
The Prince Albert Fishing Society has about 10,000 members across the country. Any fish caught is returned to the water.