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Government of Western Australia - Department of Fisheries
Close-up view of a green mud crab claw showing the distinctive spines
​The green mud crab has more than one large sharp spine on its elbow and big, distinct spines on its claw.
Wednesday 5 July 2017

Don’t muddy the waters

Despite their names, mud crabs don’t actually look green or brown. Although similar in appearance, there are some notable differences that will help with identification – their infamous big claws being the key.

The green mud crab has more than one prominent sharp spine on the claw ‘elbow’ and large, distinct spines on its claw. The brown mud crab has one small blunt spine on the elbow, or no spines at all. The spines on its claws are also small or just look like bumps.

In addition, the green mud crab has long, narrow ‘lobes’ between its eyes, but the brown has short, broad lobes. The walking legs of the green are obviously patterned (mottled), while the legs of the brown may have a very faint pattern.

The minimum size you’re allowed to keep them differs, so for this reason, fishers need to be able to tell them apart. Green mud crabs have a larger size limit (150 mm carapace width) because they mature at a larger size. Browns rarely grow that large, so have a 120 mm size limit.

Each mud crab should be measured across the widest part of the shell, from tip-to-tip of the carapace spikes, using a gauge from a tackle store. Any mud crab below the minimum legal size and those carrying eggs must be released immediately.

For more information see our recreational fishing rules.

You can also download our  Recreational fishing guide or pick up a copy of the guide from our offices and participating information outlets.

Last modified: 13/07/2017 9:18 AM

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