The majority of dead fish have been cleared from Trangie's Goan Waterhole as local conservationists look at flushing new water into the lagoon following a fish kill around mid-October.

Narromine-based Tony Lees said there were still a few fish floating out of reach on deeper water on Thursday 30 Thursday.

"I wasn't too keen to be swimming out there," he said.

"I reckon we pulled 200 out. We didn't count them.

"Probably should have in hindsight, but, honestly, it wasn't a pleasant job. I wasn't going to be hanging around any longer than I needed to.

"Our issue is we don't know how many were in there, so we don't know if they're all dead or if indeed some have survived."

A spokesperson for NSW Department of Primary Industries and Regional Development (DPIRD) confirmed that authorities inspected the site on the 24 October.

A native Cod caught up in the fish kill. [IMAGE: supplied] 

They said up to a few hundred fish were affected.

Most were European Carp, but also "low numbers" of natives like Murray Cod, Bony Herring and Golden Perch. 

The fish were disposed at the local tip.

"The cause of death is likely linked to poor water quality, including low dissolved oxygen, with shallow water levels in the lagoon and high temperatures recently experienced in the area," the spokesperson said.

Mr Lees also said that increased temperatures around mid-late October killed floating duckweeds, which sucked oxygen from the water when they sunk and decomposed.

Mr Lees, who is involved in local environmental preservation, said a licence has been secured to deliver ten megalitres from the Macquarie River into the Waterhole - the equivalent of four Olympic swimming pools.

He said it will be used to flush lower-oxygen water that drains into the system from the township.

"It's not good quality water. It picks up a lot of nutrients, a lot of pollution, oil on the road from cars," Mr Lees said.

"It's been 20 years since we've had a natural flow through the Goan to replace that water."

He says overextraction for irrigation has prevented water in the Macquarie from reaching the Waterhole.