IT might look like something fishy is going on, but thousands of fish, including 1000 barramundi, were found dead as a natural result of the floods.

Rockhampton fishing expert Bill Sawynok said the fish kill at Woolwash Lagoon was reported by recreational fishers on Saturday with most fish appearing to have died in the past two to four days.

Mr Sawynok, of Infofish Australia, said it was the most significant fish death event he had seen in the area since 1999 when about 1500 dead barramundi were recorded at a site on Port Alma Road.

No water quality data was collected, however, it is expected the fish deaths were a natural occurrence due to inundation of grassed areas with rotting vegetation causing low oxygen levels.

“Little or no flow of the water in the lagoon is likely to have contributed to the levels of oxygen being low,” Mr Sawynok said.

Mr Sawynok’s count revealed between five and seven thousand dead fish of 11 different breeds.

About 950 of the dead barramundi were checked for tags with 38 recovered.

Mr Sawynok said not all fish in the lagoon died as there was evidence of fish still alive with swirls noted in the middle and further up the lagoon away from the area of dead fish.

“It’s devastating,” Mr Sawynok said.

Woolwash Lagoon is about 6km south of Rockhampton and is part of an extensive lagoon system that exists on the Fitzroy River floodplain.

It is connected to other lagoons and Gavial Creek during periods of flooding of the Fitzroy River or during heavy rainfall events that allow the lagoons to be connected. Most fish that died were washed up near the southern end of the lagoon.

The site is an important barramundi nursery area and has been monitored through tagging of fish from about 1986/87.