Lucknow, Jun 25 (IANS): Authorities in Uttar Pradesh Monday ordered a probe into the death of thousands of fishes which have died in the river Gomti here.

The possible reasons that could have led to such largescale deaths, Jal Nigam officials said, would be looked into.

The deaths came to light when morning walkers and other residents who take bath in the river banks at Tuliyaghat saw thousands of fishes floating in the water.

No sooner did the news spread that fishermen jumped into the river with nets to gather them.

"If true, this matter is serious and a thorough probe would be ordered into the death of the fishes," said Rajendra Kumar, chief engineer of the Jal Nigam unit.

Greens say that in the past few days the water level of the river had gone down considerably, leading to oxygen scarcity.

In the past weeks, there have been talks of water being released into the river by the Sharda canal but the depleting water level of the Gomti speaks otherwise.

Officials say that from time to time they check the oxygen levels in the river and it invariably comes around 5-6 miligram per litre, which is considered safe.

Fishes, they say, die after the oxygen level slips below the 3 mg per litre.

There is an immediate need for dredging in many parts of the river, official sources told IANS, but added that the Jal Nigam was ignoring this for a long time.