The prolonged heat and low rainfall that UK experienced in July not only distressed humans but has also affected the otherwise peaceful conditions of freshwater fishes in the lakes and rivers. On Wednesday, the Environment Agency reported at least 50,000 fishes have died off the British coast due to dangerously low oxygen levels in the waters.

The thousands of fish deaths were collected from 15 separate incidents in July, according to the Environment Agency.

To curb further deaths, the agency installed water-aerating equipment to improve the living conditions of the still alive fishes.

UK July Heatwave Kills Thousands of Freshwater Fish, Environment Officials Race to Save What Remains

"Long periods of hot weather with low rainfall can be deadly for fish," Geoff Bateman, head of fisheries and biodiversity at the Environment Agency, said.

Together with its partners, the agency put in place monitoring schemes as well as equipment in Welney, Norfolk; Pitville Park Lake in Cheltenham; and, Tiptree village pond in Essex.

Although July's heat wave was followed by a heavy rainfall, it however "caused an increase in diffuse pollution and sediment washed off roads, from sewerage systems and from agricultural land, which also lowers oxygen levels," the Environment Agency said.

It advised owners of ponds and fisheries to keep a close watch especially during warm weather.

Fishes in distress gasp at the water's surface or swim on their sides or upside down.

Fish can endure short periods of reduced oxygen. Depleted oxygen levels are the most common cause of fish kills. Oxygen levels normally fluctuate even over the course of a day and are affected by weather, temperature, the amount of sunlight available, and the amount of living and dead plant and animal matter in the water.