The taskforce's first interim report tabled in State Parliament today showed it was "possible" chemical sprays caused mass fish kills and deformities in fish larvae spawned at the Sunland Freshwater Fish Hatchery, although the report failed identify the chemical at fault or its source.

"The fish died for a reason, and thousands of bass larvae grew two heads for a reason," aquaculture veterinarian Matt Landos said.

"It remains my professional opinion that only through the involvement of pesticides can the losses and events witnessed at Sunland be explained at this time."

Hatchery owner Gwen Gilson last year blamed use of the chemical pesticide endosulfan and the fungicide carbendazim on macadamia plantations, flanking her property, for the severe deformities in the fish larvae.

"Every time we have used water that has been exposed to the (carbendazim) spray, we have the same results," Ms Gilson said.

But Queensland's Chief Veterinary Officer, Dr Ron Glanville, said the evidence was circumstantial.

"The fish deaths and deformities at the Noosa River hatchery have been under investigation by DPI&F for some time but the cause is yet to be determined," Dr Glanville said.

The taskforce's report confirmed the low levels of agricultural chemicals were found at one of three tributaries of the Noosa River two kilometres downstream from the hatchery, where passive water samplers were placed.

The tests show carbendazim at 0.4 of a nanogram per litre, atrazine at 9.65 nanograms per litre, and Metolachlor at 14.75 nanograms per litre.

A nanogram is one billionth of a gram.

The level of carbendazim is roughly equivalent to a teaspoon of sugar dissolved in a litre of water - then divided by 2500 million, the State Government said.