Supplements for Emerald Crabs?

[seamandrew]

Hi all,
I have two emerald crabs and a sally light foot crab with about 10 blue leg hermit crabs in a 55 gallon aquarium. I've just lost an anemone crab and another emerald crab and in past weeks have lost 2 more emerald crabs, a sally light foot crab, and a porcelain crab. My water chemistries are good and the hermit crabs as well as other inverts in the tank are doing well (brittle star, feather duster, snails). I'm worrying that the reason for the larger crabs dying off is lack of algae to eat. I do have green slime algae that grows periodically and I see the sally light foot eating it at times, but does anyone supplement their crabs' diets with dried seaweed? If so, what brand do you buy and how much do you give them?
I should mention that the hermit crabs are doing exceedingly well. I've never had more than 3 emerald crabs at a time and 1 sally light foot at a time. The Sally light foot is in the tank because of it's excellent work as a tank cleaner and the emerald crabs have the same job, but they're also their for show (they're so cool looking). I want to make sure I'm not making some mistake and forgetting to feed them dried seaweed. I don't want them to die anymore. They also tend to live for a few weeks before I lose them but they should live much longer than that! I know emerald crabs have penchant for bubble algae, but I haven't got any in my tank and probably don't want any either.
I do feed the fish (copperband, two clownfish, royal dottback, yellow goby, and one yellow-tail blue damsel) a live clam on the rare occasion and I've seen the emerald crabs dig into that. I've also seen them pick up the rare brine or mysis shrimp that comes there way. Same for the masago (Sushi fish eggs) I put in on the rare occasion.
Please advise.

 

[natemd]

My crabs always love it if I can get something meaty to sink down to the bottom of the tank for them to feed on. I usually never put food in the tank though specifically for them, they just get what my fish can't eat before it sinks.

 

[seamandrew]

Nate, do you find that they die after just a few weeks though? I lost the anemone crab on Monday and I tried hand feeding it a chopped piece of clam and it tossed it away. The next day, it was dead. I lost an emerald crab on Wednesday, but he got into a scuffle with someone as he lost a claw and a leg recently. We called in One-Armed Jack.

 

[renogaw]

i'd say something is not good if:
I've just lost an anemone crab and another emerald crab and in past weeks have lost 2 more emerald crabs, a sally light foot crab, and a porcelain crab. My water chemistries are good

what exactly are your levels? "good" is ok, but perfect is better. even a little nitrates are bad. how often do you do water changes? what are your calcium, iodine, salt levels?
do you have a pistol shrimp in your tank? or, heaven forbid, a mantis?
your porcelain crab is MAINLY a filter feeder, so they are tough to keep if you don't have much in the water (no dt's, floating algae, etc). the emerald and sally light foot need meat and algae, and whatever else they can eat.

 

[renogaw]

i meant to say your anenome crab AND porcelan crabs are mainly filter feeders btw.
so yea, giving it meat is not helpful, it cannot eat it.

 

[seamandrew]

I put two porcelain crabs in the tank about 6 weeks ago. 4 weeks later, I found the remains of one and was stunned as I hadn't seen either in the 4 weeks and assumed they had died and were buried under the live rock. So there may be another alive somewhere, but I don't go around looking for it. This anemone crab looked a lot like an emerald crab, but the claws were smaller and it was pinkish brown in color (Mithrax cinctimanus). I got it from this website. It wasn't like the typical anemone crab filter feeders you know with the massive claws (in relation to their anatomy). Maybe it too was a filter feeder but seeing as it's in the Mithrax genus with Emerald crabs, I didn't think so.

 

[seamandrew]

Originally Posted by renogaw
i'd say something is not good if:
what exactly are your levels? "good" is ok, but perfect is better. even a little nitrates are bad. how often do you do water changes? what are your calcium, iodine, salt levels?
do you have a pistol shrimp in your tank? or, heaven forbid, a mantis?
your porcelain crab is MAINLY a filter feeder, so they are tough to keep if you don't have much in the water (no dt's, floating algae, etc). the emerald and sally light foot need meat and algae, and whatever else they can eat.
Water tested earlier today:
Salinity 1.025
pH 8.2
Temp. 80 F
Ammonia less than 0.01 ppm
Nitrite less than <0.1 mg/L
Nitrate about 10 mg/L
Oxygen at 6.6 mg/L
Alkalinity at 3.6 meq/L
calcium 500 mg/L
phospate 0.1 mg/L
I do 10% water change about 5 gallons each week. Sometimes more. No shrimp in my tank. I don't know if you remember me renogaw but I had an Aiptasia infestation and I couldn't keep my peppermint shrimp alive. Aiptasia well under control thanks to Joe's Juice and my Copperband Butterfly.
I know Phosphate isn't perfect and I wish I could say Ammonia and Nitirite were zero, but I've never had those at 0. Am I supposed to test Iodine?

 

[natemd]

I still have three of the four emeralds I put in my tank around 6 months ago. Watch your blue leg hermit crabs to see if they are the culprits. I used to have scarlet hermit crabs in my tank until my blue leg hermits decided they didn't like them.

 

[seamandrew]

The largest of the blue legged hermit crabs is about 1/4 the size of my smallest emerald crab. I thought blue legged hermit crabs were rather docile and completely reef safe. I know scarlet hermit crabs are not fully reef safe.

 

[natemd]

The Blue legs will stay small. I know this web site has them listed as a bold temperment. In my experience though mine have been semi aggressive. I might have just gotten all the 'bullies' of the blue leg hermit world

 

[seamandrew]

So no one thinks it's a food problem? No need to give dried seaweed like you do some tangs and parrotfish?

 

[donald]

every now and again I give my emeralds small pieces of silversides or raw shrimp that is left over, but I don't do it all the time.

 

[saltymac]

I dont think its a food problem. If you start feeding your cleaners, they wont clean. Ive had 2 out of 3 small emeralds for over a year now and 3 large ones for about nine months. 3 peps for about the same time and a cleaner for 4 months, I dont test for 1/2 the stuff you do. Ive never had any, but have read that hermits will kill. And not for the sake of getting a new shell, (snail) they will kill just to kill. But, like I said, Ive never owned any and it was for that reason. Ive also read that snails and crabs and shrimp dont live much longer than 2 years........but Im not sure about that. Good luck.

 

[sepulatian]

They are scavengers. You do not have to suppliment anything for any of them. You have green slime algae? What kind of water are you using. Blue leg hermits stay as small as the largest shell that they can steal. I currently have a blue leged hermit in a quater sized turbo snail shell that he is outgrowing. They are not as docile as they may look. Why have your ammonia and nitrite never been at zero? That would be a reason to stress any live stock. How old is this system?

 

[seamandrew]

The system is over 2 years old, but whenever I've tested for nitrite or Ammonia, it's never 100% clear so I do not consider it 0.
I either buy the Nutri-System 4.4 gallon pre-mixed water or get reverse osmosis salt water from my Local Fish Store (voted number 3 in the country). So I do not put any tap at all in the tank. I have power compacts and I wonder if I should leave only the actinic lights on for most of the day and the daylight only for 6-7 hours instead of the 8-10 they are on.
I've never know blue-legged hermit crabs to be aggresive in any way. Interesting...
Sepuatian... what do you mean it would be a reason to stress any live rock?
Thanks for the tips on supplementing the crabs. I do periodically drop a piece of live clam, but that's like once a month.

 

[sepulatian]

Sepuatian... what do you mean it would be a reason to stress any live rock?
I said it would be a reason to stress any live stock, not rock. The ammonia and nitrite readings. Get those double checked at the LFS. You may need a new kit.

 

[renogaw]

have you EVER used copper in your tank?
iodine helps with molting, and if it is a new crab, then sometimes they have an early molt. but, since you do water changes every week, then your salt mix should have some iodine in it.
i sorta disagree with "don't feed your clean up crew". my tank is virtually algae and detritus free as far as i can tell. i don't see anything wrong with giving my bigger crabs something to munch on when i feed my anenomes silversides, and when i feed my sun coral i always squirt some food onto the sand for the hermits/nass snails.

 

[buckster71]

Originally Posted by seamandrew
The largest of the blue legged hermit crabs is about 1/4 the size of my smallest emerald crab. I thought blue legged hermit crabs were rather docile and completely reef safe. I know scarlet hermit crabs are not fully reef safe.
Hmmm..
I think you have this backwards as the blues are the more opportunistic of the two.

 

[seamandrew]

Originally Posted by sepulatian
I said it would be a reason to stress any live stock, not rock. The ammonia and nitrite readings. Get those double checked at the LFS. You may need a new kit.
Sorry about that Seuplatian, it was late when I read that!
It's been the since for ever, I just got the new Ammonia kit (Red Sea) about 3 weeks ago. The Nitrite one is older, but it should be buying this soon. My LFS said they were low enough that I didn't need to worry (I did take water samples there when I was having trouble keeping Peppermint Shrimp (to battle the Aiptasia). Nitrates at the time were really high so I've worked to bring this down, larger water changes, less food in tank, more frequently cleaning of filter components, and using the AZNO3 (Absolute Zero Nitrates) by Bayside supplement. It's gone down from above 50 mg/L to 10 mg/L.

 

[seamandrew]

Originally Posted by buckster71
Hmmm..
I think you have this backwards as the blues are the more opportunistic of the two.
My Invertebrate Reference guide says blue-legged and red-legged hermit crabs are rather docile, except for snails, but Scarlet Hermit Crabs are more aggressive, due to their larger size.