Nasty nighttime surprise

[0sprey]

I crept up on my tank with a flashlight last night; I was watching all the different pods scurrying around (quite entertaining, try it sometime if you haven't already), and I started to shine the flashlight into all the little hidey-holes in the rock. Then I saw something move in the cracks, slowly sheltering itself from the light...
Something big.
And spiderlike.
I have at least two enormous crabs in my tank. Possibly more. Their carapaces alone are at least 2 inches wide, definite fish-killer size. They have all the supposed earmarks of 'dangerous' crabs, too... hairy carapace, dark pincers. I'm stunned that I've had all the rock in my tank for at least ten months (no coral additions since four months ago), and yet these things have escaped my notice. I scrubbed down all my rock too, very carefully, and never saw any crabs.


I've heard of tipping a baited beer glass to catch them, but I don't have a DSB, so I'm not sure I'll catch much more than my hermits and bristleworms. Should I try to bait them out? They don't seem to move very fast, but I remember thinking that about my brittle star before I scared him for the first time... Any other suggestions?

[albert_dao]

Convert to a peacock mantis tank :D

But no, seriously, what I usually do is drop all my rock work across the bottom of the tank, making sure to spread it out as much as possible. Once you've done that, it's just a matter of finding the crab at night, grabbing the rock and smashing the crab with a screwdriver or something.

I don't spend a lot of time extracting the crab. If it's stubborn, I just maul it with something sharp. The bristle worms take care of the rest.

[0sprey]

:eek: Dismantle all the rockwork? I have 150lbs... Somehow trapping seems a lot easier... maybe I could prop one end of a beer glass up on some rock rubble?

[bv_reefer]

speaking of nightime surprises, around 1 in the morning i came with a flashlight
and as i shined it saw 10x as much nocturnal life than i thought i'd had, 7-8 long string-like bristleworms some tick like things, and a couple of purple flat bristeworms and a bunch more...good thing they only come out at night cause they honestly didn't make my night :neutral:

[MikeP]

maybe I could prop one end of a beer glass up on some rock rubble?

Try this with the beer glass or a clean jar. And bait with some sinking food like algae wafers. I have caught a few like this. I have also taken out the rock they are hiding in and shook or poked the crab out into a bucket. Then into the sump they go :)

[Aquattro]

Have you lost any fish in the last 10 months? Have they done anything bad? I've always been pro-crab, so I leave them alone unless I know they're bad.

[0sprey]

Have you lost any fish in the last 10 months? Have they done anything bad? I've always been pro-crab, so I leave them alone unless I know they're bad.
Hard to say... I had a shrimp disappear, but that's about it.
If fish had gone missing, they wouldn't get a chance for the sump. I'd bash them to bits. As it is, I'm going to try to humanely trap them, then keep them in the sump (or maybe in the QT for a while so I can watch them... it's empty right now, anyway).
I'm going to give the beer glass a go. Although my family is all for bait fishing them out (and it does sound like fun), I would have to find them in a relatively open space during the day to pull that off.

[0sprey]

Baited a vase, and tipped it up against some rocks last night. One down... don't know how many are left to go!

[Zylumn]

Did you get a pic.?