Emerald Crab attacks!

tls · 02/12/2007, 09:29 AM

I thought they were safe with fish, but last night my emerald crab attacked a blue tang i just bought. I just put him in yesterday afternoon and seemed fine. i checked later and the tang was in the rocks and looked like he was stuck. i picked the rock up and my emerald crab had him by the cohones. i flicked the crab in the head and he released the tang. Im worried about these emeralds now. should i pull them out?

mikeshook · 02/12/2007, 09:38 AM

Hmm....I would first rule out that the Tang wasn't sick to the point of being close to death....and the crab was doing you a favour by starting to eat it. It's very common for a NEW blue Tang to be fine at night and dead by morning....Not that crabs don't eat fish....it's just that most fish are too fast or too big for an emerald crab.

tls · 02/12/2007, 09:41 AM

I just got him that day and the LFS store has had them for a while so i dont think he was sick. probably stressed from the move. At night do will a tang hide in the rocks to sleep?

amazingbobby · 02/12/2007, 09:55 AM

I had an emerald crab. He would cower in the nearest crevice if a fish came near. Unless your tang was small and stupid or as mikeshook said, "near death," I am suprised by the attack.

RichConley · 02/12/2007, 09:59 AM

Yeah, your tang is on its way out. Tangs dieing overnight because of low oxygen is pretty common.

tls · 02/12/2007, 10:05 AM

The emerald has tried to make grabs at my blenny when he swims by as well, but hasnt suceeded. may i need to get a crab behaviorist to correct my crabs dominence in the tank.........

dc · 02/12/2007, 10:12 AM

The trying to grab, may just be trying to scare. That's what it looks like to me. Make himself look menacing to others. Now they won't turn down a meal that's for sure.

benray4fun · 02/12/2007, 10:27 AM

My emerald ate my skunk cleaner shrimp, so I'm not surprised in the least and the shrimp was pretty big!...

tls · 02/12/2007, 10:37 AM

its crab on crab crime spree in my tank. the emeralds vs. the hermits. emeralds always doing home invasions on the hermits .when will it stop?

The Saltwater Kid · 02/12/2007, 10:43 AM

emeralds are EVIL pure and simple. I would try to get him out if you can...unless you actually have one that pays attention to any bubble algae you have. I HAD one until one night I caught him trying to trim the tentacles of my Sun Polyps...back to the LFS he went!!!

RichConley · 02/12/2007, 11:01 AM

Quote:

Originally posted by The Saltwater Kid
emeralds are EVIL pure and simple. I would try to get him out if you can...unless you actually have one that pays attention to any bubble algae you have. I HAD one until one night I caught him trying to trim the tentacles of my Sun Polyps...back to the LFS he went!!!

If theyre trying to eat your corals, you aren't feeding your tank anywhere near enough. Buy a bigger skimmer, and feed heavier.
I have NEVER had a single problem with crabs/hermits/etc. Why? Because I skim heavy and feed heavy. Stop trying to starve your reef. These are supposed to be food rich environments.

tls · 02/12/2007, 11:27 AM

what kind of food supplements should i be feeding the crabs?

The Saltwater Kid · 02/12/2007, 11:55 AM

Well Rich the rest of the crabs weren't attacking/eating anything else they aren't supposed to and when i posted about my emerald there were others who had experienced the same problems so I guess I'm not alone.

lawdog · 02/12/2007, 11:57 AM

Just feed enough to your tank in general. I feed a chunk of mysis and algae infused brine or Prime reef every other day. I skim heavily and everyone is happy healthy and fat...

Very few crab on crab hits... I have about 20 emeralds and about 50 hermits of all different varieties... I love the little guys. It would not be a reef tank without them IMHO. Along with about 100+ snails (trochus, cerith, astrea)... not much snail death either. I have so many snails (my trochus constantly are reproducing) that I don't notice one or two go missing every once in awhile when a hermit might need a new shell. It is all part of the ecosystem as far as I am concerned.

jimwat · 02/12/2007, 12:12 PM

I've always had emeralds and have never seen one attack a healthy fish (or shrimp). I have one that is pretty big and ornery that will take an aggressive posture sometimes when fish swim near, but I've never seen it snap at anything. It will, however, pull a silverside right out of the mouth of my BTA if I do not chase it off first.

TimTen · 02/12/2007, 12:14 PM

how do you guys remove emerald crabs?

RichConley · 02/12/2007, 12:15 PM

Exactly. If your hermits are killing each other, snails, etc, and your crabs are attacking things, you're not putting enough food in your tank.

I read an article a while back stating that 14kg of particulate food flows through a cubic meter of reef every day. Thats a TON of food, and thats what these animals are used to. Hermits/Crabs are smart enough to find other means of feeding themselves if you dont feed them.

Feeding very heavy and skimming very heavy is much better than trying to limit algae by underfeeding. Well fed animals are less aggressive, and less territorial.

The fact that other people have had the same problem with emeralds as you doesnt mean they aren't all doing something to cuase it (IE underfeeding)

Justdrew · 02/12/2007, 12:28 PM

To keep my emerald fed I rubber band a piece of nori to a rock and drop it to the bottom. He makes a quick meal of it and any that is left the slower hermits and snails end up cleaning up.

Later
Drew

The Saltwater Kid · 02/12/2007, 01:35 PM

I believe I will try the piece of nouri wrapped around a rock (or some other way to get it near the bottom of the tank) as it sounds like a good idea that would benefit most everything in the tank.

rustybucket145 · 02/12/2007, 01:43 PM

Right on Rich, I'll add to that, I feed my emeralds, tangs, hermits and snails a variety of algae, not just the nori. You can go to an asian market and get bags of different types of seaweed. Just make sure it's not flavored. I think giving them a varied diet keeps them happy and eating what they are supposed to in the tank and not each other.

I also agree on the tang probably not being 100% healthy. Could be from the stress of the move, could be acclimation....etc. who knows? But I was just thinking.... if my largest emerald just so happened to grab onto my yellow tang, the crab would be going a one hell of ride.

And I guarantee that he wouldn't be holding on for long!

A healthy tang should have absolutely no problem getting away from an emerald. Heck, they don't even have the proper claws to grab onto a fish.

On the crab trying to get at the sun coral.... are you sure he wasn't trying to get some food that the coral had caught? Quite often I have to fend off over-zealous hermit crabs that want some of the mysis that my sun caught. No biggie, just flick them off with the baster or tongs and give the coral time to gobble it down.

The Saltwater Kid · 02/12/2007, 04:08 PM

Nope, he wasn't getting any food as the Sun Polyps weren't eating at the time, just extended. I originally bought him to take care of a small outbreak of bubble algae which he completely ignored. I know there is a fine line between overfeeding and encouraging nuisance algae to grow and feeding just the right amount to keep everything healthy and happy...finding that happy medium is the key but it's not easy!

Kigs · 02/12/2007, 04:18 PM

I had an emerald crab attack corals to fish. Well, it made an attempt to attack fish but it was too slow. Coral wise, it wanted to chow down some of the LPS and softies in the tank. It found itself in a mantis tank within the hour.

benray4fun · 02/12/2007, 05:29 PM

My emerald killed a mantis..."they both had to go"...

sulp · 02/12/2007, 06:25 PM

Uh Oh....I'm worried now. My new Emerald's carapace was approx. 1" when I got him 3 weeks ago. A perfect size and an efficent part of my clean up crew. I noticed him missing for a whole day an figured he was molting. Boy was I right! He emerged more then double sthe size he was....No exaggeration at all...MORE THEN DOUBLED his size. I have NEVER EVER seen such a thing happen in a single molt. He is now HUGE and a real PIA.

Time to rinse out a snapple bottle, go to the Acme and buy a single shrimp (I love the clerks reaction to this) and get to work.

I'll post pictures after I snag him.

ninjamini · 02/12/2007, 06:37 PM

My emerald killed my sally light foot that I had for over 2 years. One morning I just found him tore up.

02/12/2007, 09:29 AM	#1
tls Registered Member Join Date: Dec 2006 Location: orlando Posts: 57	Emerald Crab attacks! I thought they were safe with fish, but last night my emerald crab attacked a blue tang i just bought. I just put him in yesterday afternoon and seemed fine. i checked later and the tang was in the rocks and looked like he was stuck. i picked the rock up and my emerald crab had him by the cohones. i flicked the crab in the head and he released the tang. Im worried about these emeralds now. should i pull them out?

02/12/2007, 09:55 AM	#4
amazingbobby Registered Member Join Date: Jan 2006 Location: N.California Posts: 227	crabs... you just can't trust the shady suckers I had an emerald crab. He would cower in the nearest crevice if a fish came near. Unless your tang was small and stupid or as mikeshook said, "near death," I am suprised by the attack. __________________ Control for smilers can't be bought Current Tank Info: 29 gal Reef, 30"Coralife Deluxe Aqualight, Aqua C Remora Skimmer, 24 gal Cube w/ 150w Sunpod. LPS, softies, bristleworms x 7.34 million, and other weird creatures.

02/12/2007, 09:59 AM	#5
RichConley Registered Member Join Date: Sep 2004 Location: Bostonian in Chicago going to DC Posts: 9,908	Yeah, your tang is on its way out. Tangs dieing overnight because of low oxygen is pretty common. __________________ NO TANKS!!!

02/12/2007, 10:12 AM	#7
dc Moderator Emeritus Join Date: Mar 2001 Location: Wyoming Posts: 44,684	The trying to grab, may just be trying to scare. That's what it looks like to me. Make himself look menacing to others. Now they won't turn down a meal that's for sure. __________________ Debi ~60 Cube~ Why? Because I said so of course. -Sent via Tapatalk Smoke Signals-

02/12/2007, 10:43 AM	#10
The Saltwater Kid Registered Member Join Date: Apr 2003 Location: Barre, VT Posts: 2,586	emeralds are EVIL pure and simple. I would try to get him out if you can...unless you actually have one that pays attention to any bubble algae you have. I HAD one until one night I caught him trying to trim the tentacles of my Sun Polyps...back to the LFS he went!!! __________________ Oceanic Biocube 14g Nano Tank w/middle chamber refugium mod 2 Ecoxotic Power Pro LED Modules (1 - 12K/Royal Blue combo, 1 - Royal Blue) MaxiJet 900 return, VorTech MP10 circulation Livestock: Higher End Z's & P's, few mushrooms, Aussie Duncan, Maxi Mini Carpet Anemone

02/12/2007, 09:38 AM	#2
mikeshook Registered Member Join Date: Jan 2004 Location: Charlotte/Houston Posts: 147	Hmm....I would first rule out that the Tang wasn't sick to the point of being close to death....and the crab was doing you a favour by starting to eat it. It's very common for a NEW blue Tang to be fine at night and dead by morning....Not that crabs don't eat fish....it's just that most fish are too fast or too big for an emerald crab.

02/12/2007, 09:41 AM	#3
tls Registered Member Join Date: Dec 2006 Location: orlando Posts: 57	I just got him that day and the LFS store has had them for a while so i dont think he was sick. probably stressed from the move. At night do will a tang hide in the rocks to sleep?

02/12/2007, 10:05 AM	#6
tls Registered Member Join Date: Dec 2006 Location: orlando Posts: 57	The emerald has tried to make grabs at my blenny when he swims by as well, but hasnt suceeded. may i need to get a crab behaviorist to correct my crabs dominence in the tank.........

02/12/2007, 10:27 AM	#8
benray4fun Registered Member Join Date: Mar 2005 Location: Hartford, CONNECTICUT Posts: 1,147	My emerald ate my skunk cleaner shrimp, so I'm not surprised in the least and the shrimp was pretty big!...

02/12/2007, 10:37 AM	#9
tls Registered Member Join Date: Dec 2006 Location: orlando Posts: 57	its crab on crab crime spree in my tank. the emeralds vs. the hermits. emeralds always doing home invasions on the hermits .when will it stop?

02/12/2007, 11:27 AM	#12
tls Registered Member Join Date: Dec 2006 Location: orlando Posts: 57	what kind of food supplements should i be feeding the crabs?

02/12/2007, 11:55 AM	#13
The Saltwater Kid Registered Member Join Date: Apr 2003 Location: Barre, VT Posts: 2,586	Well Rich the rest of the crabs weren't attacking/eating anything else they aren't supposed to and when i posted about my emerald there were others who had experienced the same problems so I guess I'm not alone. __________________ Oceanic Biocube 14g Nano Tank w/middle chamber refugium mod 2 Ecoxotic Power Pro LED Modules (1 - 12K/Royal Blue combo, 1 - Royal Blue) MaxiJet 900 return, VorTech MP10 circulation Livestock: Higher End Z's & P's, few mushrooms, Aussie Duncan, Maxi Mini Carpet Anemone

02/12/2007, 11:57 AM	#14
lawdog Registered Member Join Date: Sep 2004 Location: Rootstown, Ohio Posts: 794	Just feed enough to your tank in general. I feed a chunk of mysis and algae infused brine or Prime reef every other day. I skim heavily and everyone is happy healthy and fat... Very few crab on crab hits... I have about 20 emeralds and about 50 hermits of all different varieties... I love the little guys. It would not be a reef tank without them IMHO. Along with about 100+ snails (trochus, cerith, astrea)... not much snail death either. I have so many snails (my trochus constantly are reproducing) that I don't notice one or two go missing every once in awhile when a hermit might need a new shell. It is all part of the ecosystem as far as I am concerned. __________________ Regards, Craig "Will be giving Free Legal Advice Tomorrow..." Current Tank Info: Marineland 200DD Reef Tank, In Wall, Still Rocking dual 250W MH lights; LifeReef skimmer, Custom Sump/Refuge, Reeflo Dart Return to Seaswirls; Tunze Streams (waiting for new Riptide!); Lifereef Calc Reactor; Keeper of Magnifica Ritteri!

02/12/2007, 12:12 PM	#15
jimwat Premium Member Join Date: Apr 2003 Location: South Florida Posts: 1,270	I've always had emeralds and have never seen one attack a healthy fish (or shrimp). I have one that is pretty big and ornery that will take an aggressive posture sometimes when fish swim near, but I've never seen it snap at anything. It will, however, pull a silverside right out of the mouth of my BTA if I do not chase it off first. __________________ "Give a man a fish and he will eat for a day. Teach a man to fish and he will sit in a boat all day and drink beer." Current Tank Info: 65 gal with 192w PC 10k, 192w VHO actinic, Blue-Moon LED, Tunze 6060 on WavySea, AquaController 3. 20gal sump, Natureef CDECX-1, Phosban Reactor, Remora, Kalk Drip, Ozone.

02/12/2007, 12:14 PM	#16
TimTen Registered Member Join Date: May 2006 Location: Alameda, Ca Posts: 557	how do you guys remove emerald crabs?

02/12/2007, 12:15 PM	#17
RichConley Registered Member Join Date: Sep 2004 Location: Bostonian in Chicago going to DC Posts: 9,908	Exactly. If your hermits are killing each other, snails, etc, and your crabs are attacking things, you're not putting enough food in your tank. I read an article a while back stating that 14kg of particulate food flows through a cubic meter of reef every day. Thats a TON of food, and thats what these animals are used to. Hermits/Crabs are smart enough to find other means of feeding themselves if you dont feed them. Feeding very heavy and skimming very heavy is much better than trying to limit algae by underfeeding. Well fed animals are less aggressive, and less territorial. The fact that other people have had the same problem with emeralds as you doesnt mean they aren't all doing something to cuase it (IE underfeeding) __________________ NO TANKS!!!

02/12/2007, 12:28 PM	#18
Justdrew Dad with Triplets! Join Date: Jan 2001 Location: Las Vegas, NV Posts: 583	To keep my emerald fed I rubber band a piece of nori to a rock and drop it to the bottom. He makes a quick meal of it and any that is left the slower hermits and snails end up cleaning up. Later Drew __________________ "As Far As You Know!" -Fletch Current Tank Info: 40 Breeder, 2X Radion XR15W, Vortech MP40 & MP10, Simplicity Aquatics 240DC Skimmer, Apex Controlled

02/12/2007, 01:35 PM	#19
The Saltwater Kid Registered Member Join Date: Apr 2003 Location: Barre, VT Posts: 2,586	I believe I will try the piece of nouri wrapped around a rock (or some other way to get it near the bottom of the tank) as it sounds like a good idea that would benefit most everything in the tank. __________________ Oceanic Biocube 14g Nano Tank w/middle chamber refugium mod 2 Ecoxotic Power Pro LED Modules (1 - 12K/Royal Blue combo, 1 - Royal Blue) MaxiJet 900 return, VorTech MP10 circulation Livestock: Higher End Z's & P's, few mushrooms, Aussie Duncan, Maxi Mini Carpet Anemone

02/12/2007, 01:43 PM	#20
rustybucket145 Registered Member Join Date: Jan 2006 Location: valdosta, ga Posts: 3,707	Right on Rich, I'll add to that, I feed my emeralds, tangs, hermits and snails a variety of algae, not just the nori. You can go to an asian market and get bags of different types of seaweed. Just make sure it's not flavored. I think giving them a varied diet keeps them happy and eating what they are supposed to in the tank and not each other. I also agree on the tang probably not being 100% healthy. Could be from the stress of the move, could be acclimation....etc. who knows? But I was just thinking.... if my largest emerald just so happened to grab onto my yellow tang, the crab would be going a one hell of ride. And I guarantee that he wouldn't be holding on for long! A healthy tang should have absolutely no problem getting away from an emerald. Heck, they don't even have the proper claws to grab onto a fish. On the crab trying to get at the sun coral.... are you sure he wasn't trying to get some food that the coral had caught? Quite often I have to fend off over-zealous hermit crabs that want some of the mysis that my sun caught. No biggie, just flick them off with the baster or tongs and give the coral time to gobble it down. __________________ 400gals of various tanks in the same system. Current Tank Info: 2 175w MH, 2 VH0 Actinics, Lots of Live Rock, tons of copepods, a Fat Mandarin Goby, Niger Trigger, Yellow Tang, Falco Hawkfish, Bi-Color Pseudo, numerous soft, SPS and LPS Corals

02/12/2007, 04:08 PM	#21
The Saltwater Kid Registered Member Join Date: Apr 2003 Location: Barre, VT Posts: 2,586	Nope, he wasn't getting any food as the Sun Polyps weren't eating at the time, just extended. I originally bought him to take care of a small outbreak of bubble algae which he completely ignored. I know there is a fine line between overfeeding and encouraging nuisance algae to grow and feeding just the right amount to keep everything healthy and happy...finding that happy medium is the key but it's not easy! __________________ Oceanic Biocube 14g Nano Tank w/middle chamber refugium mod 2 Ecoxotic Power Pro LED Modules (1 - 12K/Royal Blue combo, 1 - Royal Blue) MaxiJet 900 return, VorTech MP10 circulation Livestock: Higher End Z's & P's, few mushrooms, Aussie Duncan, Maxi Mini Carpet Anemone

02/12/2007, 04:18 PM	#22
Kigs Moved On Join Date: Feb 2005 Location: LI, NY Posts: 2,182	I had an emerald crab attack corals to fish. Well, it made an attempt to attack fish but it was too slow. Coral wise, it wanted to chow down some of the LPS and softies in the tank. It found itself in a mantis tank within the hour.

02/12/2007, 05:29 PM	#23
benray4fun Registered Member Join Date: Mar 2005 Location: Hartford, CONNECTICUT Posts: 1,147	My emerald killed a mantis..."they both had to go"...

02/12/2007, 06:25 PM	#24
sulp Registered Member Join Date: Feb 2005 Location: Philadelphia area Posts: 1,254	Uh Oh....I'm worried now. My new Emerald's carapace was approx. 1" when I got him 3 weeks ago. A perfect size and an efficent part of my clean up crew. I noticed him missing for a whole day an figured he was molting. Boy was I right! He emerged more then double sthe size he was....No exaggeration at all...MORE THEN DOUBLED his size. I have NEVER EVER seen such a thing happen in a single molt. He is now HUGE and a real PIA. Time to rinse out a snapple bottle, go to the Acme and buy a single shrimp (I love the clerks reaction to this) and get to work. I'll post pictures after I snag him. __________________ There is something in the psychology of mankind to which coral reefs never fail to appeal. - Stanley J. Gardiner Current Tank Info: 12g JBJ Nano Cube 14lbs Mixed Figi & Tonga Branch - 24' Coralife Aqualite Pro 150w 10,000k HQI MH 2 96w true actinics. Going to have a mix of SPS & softies

02/12/2007, 06:37 PM	#25
ninjamini Registered Member Join Date: Jan 2005 Location: Davie, FL Posts: 2,306	My emerald killed my sally light foot that I had for over 2 years. One morning I just found him tore up.