Can native fish be nature’s pool cleaners?

Have you ever wondered why natural pools can have crystal clear water while the pond in the local park, despite constant care, sometimes appears murky and full of algae?

One reason might be that artificial ponds don’t contain nature’s vacuum cleaners - fish that naturally eat algae and detritus.

Researchers at Southern Cross University’s National Marine Science Centre (NMSC) will release juvenile hatchery-raised mullet into freshwater ponds at the Novotel Pacific Bay Resort in Coffs Harbour tomorrow (November 30) as part of a study to examine the fish’s ability to remove organic debris and aquatic vegetation from their environment.

The project is being led by Dr Ken Cowden, the aquaculture operations manager at the NMSC.

The common sea or bully mullet is a native fish with a unique detritivorous feeding habit which lends the species to use as a ‘bioremediator’, a term used when live animals process various waste products in their environment.

The ponds at Pacific Bay Resort are quite healthy, but periodically suffer from excessive nutrient inputs and aquatic vegetation growth which in turn leads to a build-up of organic sediments – a mullet’s favourite food.

Researchers hope the mullet will reduce the need to clean the ponds in the future, and lead to a general improvement in the water quality and aesthetic appeal of the ponds.

Dr Cowden said the study would run for several years, and regular water and sediment quality data would be collected through that time to establish exactly what benefits the mullet confer.

“If successful, the method could have widespread application in other waterways where excess nutrient inputs occur, and even in intensive agricultural waste processing,” Dr Cowden said.

Photo opportunity: The juvenile hatchery-raised mullet will be released into the freshwater ponds at Novotel Pacific Bay Resort at 11am, Friday, November 30.