Yellowfin Goby <em>(Acanthogbius flavimanus)</em>

Introduction

Yellowfin Goby (Acanthogobius flavimanus) is a small bodied, bottom dwelling fish native to Japan, the Korean peninsula, and parts of China. Individual specimens display a light brown to dark brown mottled pattern and can be identified by the dark spots on their back and their yellow bellies. When viewed from above Yellowfin Goby heads are wider than their bodies and they have a dark line that slopes downward from beneath their eye to the rear corner of their mouth. This species grows to a maximum length of 30 cm.

Yellowfin Goby are listed as a Class 1 noxious fish in NSW. This status prohibits live possession and sale of the species within the state.

Yellowfin Goby
Photo: Shane Murray ©

Biology

Yellowfin Goby prefer muddy or sandy estuaries, river mouths and bays. They can tolerate fresh and salt water. The species is a benthic omnivore feeding on small crustaceans such as shrimp, crabs, and other small fish. As with most fish species, adults target larger prey items than do juveniles (e.g. worms and small fishes vs. zooplankton).

Males mature after one year and females mature after two. Both freshwater and saltwater populations migrate to brackish estuarine water to spawn (5-30 ppt salinity). Yellowfin Goby males construct tunnels into which females can lay anywhere from 6,000 to 32,000 eggs. The male then fertilises the eggs and guards them until they hatch approximately 28 days later. Newly hatched individuals drift as free swimming larvae until they settle out of the water column at approximately 13-15 mm in length. By the end of their first year most will reach 10-14 cm and will grow to 16-18 cm by the time they reach two years of age. Yellowfin Goby rarely survive past three years reaching a maximum length of 30 cm (Baker 1979).

There have been few formal investigations studying the impact Yellowfin Goby have on the aquatic ecosystems of NSW. However, it is likely that Yellowfin Goby compete directly with native species for space and food resources and therefore may pose a risk of displacing native fish populations.

Where are they in NSW?

Yellowfin Goby were first detected in Australia in Botany Bay and Port Jackson in the early 1970’s. Since that time they have also been reported in the Hawkesbury and Hunter River estuaries.

How did they get here?

It is not known exactly how the Yellowfin Goby was introduced to Australian waters. However, it is possible that larvae were translocated to Australia via ballast water carried in international cargo ships.

What is NSW DPI doing?

NSW DPI will continue its ongoing monitoring of native and pest fish species in NSW. If any new populations of Yellowfin Goby are discovered through these surveys, NSW DPI will assess potential control and monitoring options.

How you can help

Prevention is the best medicine! It is extremely difficult, if not impossible, to eradicate pest fish once they become established in the wild. This fact makes it important to prevent non-native species such as the Yellowfin Goby from spreading further within NSW waterways.

You can help to protect our waterways by:

  • Being on the lookout for new species in your local waterways, if you see something strange report it!
  • Give unwanted aquarium fish to friends or a pet shop, rather than letting them go in the wild (Note: it is illegal to release live fish into NSW waterways without a permit, and heavy penalties apply).
  • If you are involved in fish stocking, obtain a fish stocking permit from NSW DPI before buying fish for restocking. Also, buy fingerlings from local suppliers rather than outside your region or interstate, to minimise the chances of introducing species not native to your area.
  • If you are a fish farmer, comply with aquaculture permit conditions designed to prevent the escape of fish (e.g. screened water outlets), and keep to your approved species list.
  • If you find any fish that you think might be a Yellowfin Goby or another non-native species, take a digital photo or freeze the fish whole and report it.

More information on how to prevent the spread of invasive pests and disease.

References and further reading

http://australianmuseum.net.au/Yellowfin-Goby-Acanthogobius-flavimanus

Baker, J.C. 1979. A contribution to the life history of the yellowfin goby (Acanthogobius flavimanus) in the San Francisco Bay-Delta area. M.S. Thesis, California State University, Sacramento, C

Cohen, S.R., and S.M. Bollens. 2008. Diet and growth of non-native Mississippi silversides and yellowfin gobies in restored and natural wetlands in the San Francisco Estuary. Marine Ecology Progress Series 368:241-254

Dotu, Y., and S. Mito. 1955. On the breeding habits, larvae and young of a goby, Acanthogobius flavimanus (Temminck and Schlegel). Japanese Journal of Ichthyology 4:153-161.

Kanou, K., M. Sano, and H. Kohno. 2005. Ontogenetic diet shift, feeding rhythm, and daily ration of juvenile yellowfin goby Acanthogobius flavimanus on a tidal mudflat in the Tama River estuary, central Japan. Ichthyological Research 52:319-324

Workman, M.L., and J.E. Merz. 2007. Introduced yellowfin goby Acanthogobius flavimanus: diet and habitat use in the lower Mokelumne River, California. San Francisco Estuary and Watershed Science 5(1): Article 1.