Is crab eating my corals

Vincent100 · Aug 31, 2016

Hi people
Had a week off work so was up late lastnight feeding my corals ,went to bed around 3.30am had a good look over the tank just before bed as I always do ,anyway got up this morning looked in the tank and saw some bits missing off 2 of my corals
I know Iv got a fare sized crab in my tank
My pic are not very clear on the sps but when you look the white bits were new growth , well they have been eaten , on one branch I can see a clear mark that looks like it's done with a claw
The other coral has a small bit missing and its now bleaching around it ...all was fine at 3.30am and I got up 11.30
Does this look like a crabs work
All my water checks out fine
Any input would be great and sorry pic are so bad

Vincent100 · Aug 31, 2016

by the way its not the crab in the first pic im talking about lol

bios · Aug 31, 2016

Impossible that crab
Im not sure for the pics but acro sems to be flatwarm bites
Echinophyllia other problems light flow or nutrients

Vincent100 · Aug 31, 2016

bios said:
Impossible that crab
Im not sure for the pics but acro sems to be flatwarm bites
Echinophyllia other problems light flow or nutrients

Thanks for your input bios

The crab I'm talking about is a big black thing with hairy legs , I saw him on top of one of my other sps the other night but he very shy and runs as soon as he sees me

The tips of the acro look like there sort of chopped off almost flat looking , like they were knocked by something, one has a mark on the bit that's bit off looks like a claw mark

The echinophyllia was growing really well ,nothing's changed in the tank , strange that there a little bit missing were its started to bleach ....... All in 8 hours
I just can't get a good pic with my phone of the acro
Bios would flatworm bite the whole tip of the acro ? Thanks for your help mate

bios · Sep 1, 2016

Place echyno under low flow and actinic light and early night stop pumps for few time and spray solution wwith aminoacid around
For acro is possible that crab you describe and not the one in photo
But my opininion is that those are flatwarm bites

Roboson · Sep 1, 2016

Without a pic of the crab in question, I can't help much.

Vincent100 · Sep 1, 2016

If he's out and sees me move he goes in to hideing , think I'm gonna do a glass trap for him but need to get my cleaner shrimp into the sump first as I know he'll just swim off with the bait

Vincent100 · Sep 2, 2016

Agin to bed at 3.00am all fine in tank ,get up this morning looked at the acro 2 new bits of growth missing bitten off , that happened within 7 hours ..... Nothing happened the night before just the night before that , all my water checked are well within range ...... This makes me think it's 100% a critter , Gotta be the crab
The bites are just to big to be flatworms ..... Must be
And i wouldn't even say there bites more like bits snapped off
This is only on the new growth

Tahoe61 · Sep 2, 2016

I called them bandit crabs, never had an issue with them I do not think they are coral eaters, anything is possible. It looks more like an alkalinity issue to me though.

Vincent100 · Sep 2, 2016

hi tahoe61
its not the crabs in the acro ,its a big black thing with hairy legs
gotta go out in a min but not for long when i get back i`ll do a full water test and post them up
my alkalinity does drop alot everyday so maybe your on to something
will quote you to get you back inhere lol
thanks

Keepswiming · Sep 2, 2016

What I heard in the past is, hairy legs=usually no good (gorilla crab).

Vincent100 · Sep 2, 2016

time to get testing me things , also just feed the fish and saw the crab im talking about ......for like 2 seconds lol
he jet black real big claws and claw arms hairy legs with what looks like sort of light brown stripes
strange looking thing

Roboson · Sep 2, 2016

Not all hairy crabs are bad crabs for example, KPaquatics sells a hairy emerald crab.

Vincent100 · Sep 2, 2016

Roboson said:
Not all hairy crabs are bad crabs for example, KPaquatics sells a hairy emerald crab.

hi roboson
iv got a few emerald crabs in the tank with hairy legs but their nothing like the one im talking about.
This ones claws and arms look near enough to big for hes body ,hes also a real dark black with like band markings round hes legs that are a light brown , i saw him when feeding the fish but hes so shy that any movement outside the tank and hes off , iv gotta get him out just to set my mind at rest

Vincent100 · Sep 2, 2016

Tahoe61 said:
I called them bandit crabs, never had an issue with them I do not think they are coral eaters, anything is possible. It looks more like an alkalinity issue to me though.

i should add iv got maybe to many coral mostly lps but about 10 sps frags aswell
some water tests
all salifert tests
magnesium sitting between 1260 1290 ppm so does that work out at 1275 ppm ......iv just dosed 5 ml of mag to try and bring it up to 1280 as iv read somewere on here thats good

gonna sort the rest out in 10 min just waiting for the mag to mix in
any tips on were my levels are best at would be good

kh/alkalinity sitting between 6.7 and 7.0 dkh so does that work out as a reading of 6.8 or 6.9 lol im not sure ......was sitting over 7.0 yesterday plus ialready dosed 3ml red sea buffer supplement 1 hour after lights on

calcium sitting between 420 and 430 on my chart so does that mean its at 425 mg/L gonna test

ph 8.1 tested with a new ph pen

gonna test nitrate nda phosphate in 2 mins

Roboson · Sep 2, 2016

Let me do some more in-depth looking. I'll try to find some culprits that match your description. Most crab hitch-hikers like gorilla crabs may attack one of your corals, but it would be really odd for them to attack several different species like this.