Abbas Khan feeds a hot wire from a rickety generator into a river, a fishing technique he argues is more environmentally friendly than others used in northwest Pakistan - though he also admits it has killed several of his friends.

Hundreds of fishermen risk their lives daily to hunt the rare fish known as "sher mahi", found in the Kabul River which flows from the Hindu Kush in Afghanistan into neighboring Pakistan, before merging with the Indus.

Some swim for hours on inner tubes, dragging nets behind them. Others use more brutal - and illegal - techniques: spraying pesticides directly into the river or, like Khan, using the electric current from generators to stun the river's inhabitants into submission.

And, for those in a hurry, there is always the brutal but effective "Khatin bomb" - dynamite.

These imprecise techniques are a threat to the river's population, say dismayed conventional fishermen who have made their living selling sher mahi, considered the best for eating in Pakistan's northwest.

"Fishing with dynamite and generators kills the entire population," said Ghani Ur Rehman.

Like dozens of his fellow fishermen, the 58-year-old spends hours each day swimming the river on an inner tube, dragging his net behind him, catching only a few kilograms at a time. He has done so for 25 years.

"Now, the fish's population has decreased and the main reason is an increase in fish hunting," he says, emptying his net on to the shore.

Along the banks of the Kabul River hundreds of visitors can be seen enjoying family days of boating and wading, topped off with a hearty meal of fresh sher mahi and other river fish at dozens of huts and restaurants.

Sher mahi, with few bones and found in Pakistan only in the Kabul River, is similar to catfish, growing to a maximum of 30 centimeters.

Some fishermen say its name come from the Persian word "sheer", or "milk", due to its rich oily taste.

Rehman says he makes on average 600 to 1,000 rupees a day - but on days when the fish are plentiful his income can soar to 10,000 rupees.

Speaking with AFP along the river, Khan admitted using a generator in the water was "scary" - but said that, despite his lack of safety gear, he has learned the correct the technique.

"Some of my friends had died because of electrofishing but now we have learnt it, now we know how to hunt in the best way," he explained, before demonstrating how to attach wires to a metal rod then place the rod in a net in the water.