Dead eels have been washed up on the shores of Lake Tutira in northern Hawke's Bay for the second time this year.
A video posted online by Kev Gilbert shows a number of dead eels in the water and along the shoreline of the lake.
The first time it happened was in January this year when there were reports of dead fish and eels in the lake known as "fish kills".
The Hawke's Bay Regional Council is aware of the issue and has staff investigating the cause of the problem.
“I went up yesterday and saw about 20 dead or dying. The dead eels are very obvious to any visitors who approach the shore with dead or dying fish observed around the boat ramp, camping grounds and northern end of the lake. There was a slight stink in the air,” says Dr Andy Hicks.
He warns that visitors to the lake should avoid handling any dead fish and that the fish are definitely not safe to be eaten by any person or family pet.
The lake is susceptible to algal blooms over the summer time especially and fish kills have happened in the passed, but the to have two large consecutive fish kills is unusual and concerning.
PH levels in the water have been tested, with a recording of 9.4 and they say any reading above 9 is extreme. However, there have not been recorded periods of extremely high temperature or low dissolved oxygen around the times of this fish kill.
Samples have been taken of the dead eels and the water and are the results are expected back in the new year.