The freshwater gold clam is quite distinctive and easily identifiable as there are no similar looking New Zealand species. 

An adult clam measures 2-3cm long, is typically dirty white, yellow, or tan in colour, and has an obvious ribbed texture on the outside of the shell. 

It is found in freshwater and estuaries or brackish waters, often buried in large clumps. You may see its shells partly exposed, or syphons (breathing tubes) sticking out from the sediment. 

The freshwater gold clam can also be found amongst debris, such as leaves, that may have settled on the riverbed. It can survive a wide range of water conditions, including temperature and saltiness. 

The freshwater gold clam is native to Eastern Asia and is widely established in North and South America and Europe where it has become a pest. 

It is a highly invasive pest that reproduces rapidly – up to 400 juveniles a day and up to 70,000 a year.  

This pest is a filter feeder that can potentially compete with native species for food and negatively impact the health of our precious lakes. 

It can clog water-based infrastructure, such as electric generation plants, irrigation systems, and water treatment plants. 

Overseas, this clam has proved difficult to control and eradication has never been achieved.  

You can help stop the spread of this pest by following the Check, Clean, Dry method below. 

When you move from one part of the river to another, or from one river or lake to another: 

Check 

• Remove any visible matter, including any clams you can see, along with plant material or mud. Drain all river or lake water. 

Clean 

• Washdown your watercraft, gear, vehicle, and trailer that has been in contact with river or lake water with tap-water onto grass, beside the waterway or at home and not into a stormwater drain system.  
• For absorbent surfaces and materials that have been in contact with river or lake water (including wetsuits and carpet on trailers), use one of these treatments*: 
  • Soak in hot tap water (55ºC) for at least 5 minutes. 
  • Soak in diluted household bleach (10%, or 1 in 10 ratio) for an hour. 
  • Freeze until solid (overnight).
• Treat residual water that always occurs when on-board ballast bladders or tanks have been pumped. 

(*Refer to the manufacturer’s instructions if needed). 

Dry 

Gear: Allow gear to dry to touch, inside and out, then leave it to dry for at least 48 hours (2 days) before using again. 

Watercraft: Dry areas inside the watercraft where water has pooled, for example with an old towel, and then leave the craft to dry for at least 48 hours (2 days). The hull of watercraft will dry when towed.