Best way to trap an Emerald Crab

Westside Guy · Mar 13, 2020

I have a few Emerald Crabs in my tank which I added last year during a bubble algae outbreak. One of them has become extremely large and the claws are huge. It has gotten so big that my wife said we could cast it in a movie as Godzilla’s opponent.

I am starting to get worried about it attacking my fish and tried to catch it with a net but it was too fast and hid deep in the rocks. Is there an easier way to trap and remove the crab which I will rehome at my LFS?

Retro Reefer · Mar 13, 2020

I‘m Working on removing a few also, so far best method has been to just reach in and grab one when I can

there are a few traps on the market that may work. you may try leaning a glass against your rock work and drop bait into it, if the crab goes in for food he won’t be able to climb out if the angle is steep enough.

AZMSGT · Mar 13, 2020

I waited till night time and pulled mine out when it was out. The key is make it so it can't see you. If you need to use a flash light but just enough light to see it. If you blast it with light it will run.

Victor_C3 · Mar 13, 2020

I’m

AZMSGT said:
I waited till night time and pulled mine out when it was out. The key is make it so it can't see you. If you need to use a flash light but just enough light to see it. If you blast it with light it will run.

Have you tried using a red light? Supposedly red is a color most marine creatures can’t see.

As far as physics goes, red is the largest wavelength and lowest energy color of visible light. It’s the first color to be filtered out by water and you go deeper in the water.

Westside Guy · Mar 13, 2020

AZMSGT said:
I waited till night time and pulled mine out when it was out. The key is make it so it can't see you. If you need to use a flash light but just enough light to see it. If you blast it with light it will run.

I have tried a few times when the lights have turned off and I couldn't believe how fast it was. In a second it was deep inside of my rocks. This has happened several times and is so frustrating! :mad:

Westside Guy · Mar 13, 2020

Victor_C3 said:
I’m

Have you tried using a red light? Supposedly red is a color most marine creatures can’t see.

As far as physics goes, red is the largest wavelength and lowest energy color of visible light. It’s the first color to be filtered out by water and you go deeper in the water.

It isn't the light that is the issue, this guy sees movement in the water and is super quick!

radsdad · Mar 13, 2020

I have caught them and I found the trick was to come in from behind.

Westside Guy · Mar 14, 2020

Retro Reefer said:
I‘m Working on removing a few also, so far best method has been to just reach in and grab one when I can there are a few traps on the market that may work. you may try leaning a glass against your rock work and drop bait into it, if the crab goes in for food he won’t be able to climb out if the angle is steep enough.

Can you recommend one of those traps?

Retro Reefer · Mar 14, 2020

Westside Guy said:
Can you recommend one of those traps?

I have never used one myself, here is a link to the type I’m talking about however several companies make them..

Pest Trap

If you have a trouble crab, worm, or even smaller fish, the Tom's Pest Trap is by far the best piece of equiptment to trap and remove small pest animals that may find their way into your reef aquarium. From small crabs and bristleworms to mantis shrimp or small fish, this trap can be a safe and...

www.bulkreefsupply.com

Spar · Mar 14, 2020

Retro Reefer said:
I have never used one myself, here is a link to the type I’m talking about however several companies make them..

I caught all my unwanted crabs using this. Worked a little better with larger crabs because they were more bold and came out quicker. But the little ones gave in pretty quick. The problem is that it is a waiting game with them since you have to trigger the door rather than a crab or fish doing so. The good part is you put something thick in that tube (like a piece of prawn), and the crab or fish can't pull it out of the trap. The crab will sit there for hours picking at it, so you don't have to sit there watching it with hawk-eyes like you probably should with a fish.

Took me ages to get all my Gorilla and Stone Crabs out of my rock... drove me near insane. But I won!