let's talk emerald crabs for a sec

[reef tank 2.0]

I bought an emerald crab for my tank back in August of this year. About a month after I found a "dead crab" on the sand bed. It was perfectly green and pinchers and all were in place. The whole body was there, including the eyes, which led me to believe the crab died. I only saw him a few times in the month or so leading up to that skeleton on the sand bed. I tried to feed him a small piece of shrimp each time I saw him, just to make sure he wasn't being starved.

once I scooped out that skeleton, I tossed it away and never thought much about it after that. I should have broke it open to see if there was any meat inside but I didn't think about that.

Over the past week or so, I noticed my toadstool polyps are starting to disappear, right on the top. the sides are nice and healthy. I did a quick search on here and it looks like others have had the same problem and fingers were being pointed at the emerald crab.

After reading that, I am now starting to wonder if this crab is still alive and what I saw was the molted Skeleton. that would be great if he was still alive, BUT, now it raises another concern about him eating the toadstool.

My tank is not that large and it's not like I can lose certain critters that I have. I see my blue leg hermits, red hermits, and assorted snails doing there thing at all times of the day. even when the lights are on. I wouldn't think the emerald would be hiding. I'd assume he would always be on clean up duty. I don't have a way of catching him in the act if he is in fact alive. My lights come on at 2:30pm and go off at 10:30pm. morning hours up to 2:00 or so, I have never noticed him. not sure how long after 10:30pm it would take for him to come out, but I never thought to look for him until now.

I have a Molly miller blenny, 2 clowns, Banggai cardinal, 2 firefish, red fairy wrasse, and 3 chromis. I cant imagine any of these guys would be eating the polyps of the toadstool. I have never seen a hermit crab on it either. other than walking across it to get to his destination. Never eating it. if it's not the emerald, cause he's could be dead, would any of these other critters be eating the toadstool? I also have a red serpent sea star but I usually see him in his hiding spot. he's always there. but he gets spot fed each night, so I know he's not starving.

any ideas?

here's a photo of the toadstool. I have a flash light shining on him but you can definitely see the affected polyps.

 

[Knucker]

Very possible it's still alive and eating coral. After you feed the fish look for anything else moving. Best trick I know is when you find it use a piece of shrimp in some tweezers. Make sure it grabs the tweezers and stick that little mean guy in the sump.

 

[BristleWormHater]

They do love long polyps like that, toadstools, gonis, euphyllia.

 

[Knucker]

They do love long polyps like that, toadstools, gonis, euphyllia.

Clove Polyp, mine looked like a lawnmower hit them.

 

[ZoWhat]

Amazon product

 

[reef tank 2.0]

For those of you that stick the emeralds in the sump. Do you ever feed them or do you let them fend for themselves and hope they survive? I have an open stock tank sump. With a decent amount of rock

 

[Knucker]

For those of you that sick the emeralds in the sump. Do you ever feed them or do you let them fend for themselves and hope they survive? I have an open stock tank sump. With a decent amount of rock

You can add some food occasionally, but they will most likely eat any pods, and algae in your sump.

 

[reef tank 2.0]

i certainly can't find this emerald crab anywhere. i see no movement when feeding, during the day, before/after lights out, nothing. its not possible that the hermits could be chomping on it, is there?

 

[BristleWormHater]

i certainly can't find this emerald crab anywhere. i see no movement when feeding, during the day, before/after lights out, nothing. its not possible that the hermits could be chomping on it, is there?

Unless it's dying I don't think so

 

[littlefoxx]

i certainly can't find this emerald crab anywhere. i see no movement when feeding, during the day, before/after lights out, nothing. its not possible that the hermits could be chomping on it, is there?

If this helps I have 3 in my biocube. I see them once in a while but usually just find what look like molts and just toss em and move on. But Im pretty sure they are there, my rockwork is very dense though

 

[TunaC]

Emerald crabs suck! Never again. Good luck figuring it out.

 

[Ryans Reef]

I’ve kept tanks since 2009, and have always had emerald crabs and never had issues with them. They key is to make sure they have something to eat. Crabs are crabs, they’re not going to starve for a lack of trying to fing something to eat. The issues I’ve heard of usually involve new or underfed tanks.

That being said I highly doubt an emerald crab is eating your toadstool. Toadstool polyps retract all the time, and it might just be the placement of the coral isn’t ideal. At any rate the emerald wouldn’t kill the toadstool. They’re incredibly resilient corals.

 

[reef tank 2.0]

i really don't think it has to do with placement. This coral, up until this polyp missing issue, has blossomed. I keep looking for whoever the culprit is to be munching, but I never see anything on it. Tonight, I was watching again, and one of my blue leg hermits crawled on top of it. the toadstool polyps located on top, retracted quickly. the polyps on the perimeter were out and unphased. I watched the blue leg and it looked like he was just picking at "something" but not exactly the polyps. he stayed on there for about 10-15 seconds, before he walked off and went back to the sand.

I thought about yanking those blue legs and throwing them in the sump but I don't know if they're the problem.

out of all the hermits I bought (red scarlet and blue leg), I am down to 2 blue leg hermits. I might have one or two reds, but don't believe so. these blues have killed most of my snails off and took their shells.

my other question is, would my tank suffer if I were to pull all crabs out (and keep them in the sump), and only keep snails in the display tank? Not sure what other reef safe cleaners there are other than snails and hermits.

 

[reef tank 2.0]

here are some updated pictures, with only white light on. if it tells you anything. the polyps are not withdrawn, but they look as is they've been cut off. the only time i've ever seen the polyps out, s when lights are on. but at that point, I don't ever see any critters on it, other than walking across it.

the gyre is on the other side of the tank and I think I have it at 30-40%. it hasn't moved in the 6 months since I've had the today. lights haven't changed either. those are on for 8 hours a day.

other corals in the area of the toady are acans, zoa's, and a trumpet. none of those are phased by whatever is bothering toady.

I do water changes every two weeks. about 30-40 gallons each time.

 

[tautog83]

crabs are overrated ( have 2 pithos and 2 emeralds, lol) . I used to do the hermit crab route and theyre just a pain. I think snails just work out better and no chance of them picking at anything . If you feel like they're the culprit just rehome them and play it safe

 

[Uncle99]

i really don't think it has to do with placement. This coral, up until this polyp missing issue, has blossomed. I keep looking for whoever the culprit is to be munching, but I never see anything on it. Tonight, I was watching again, and one of my blue leg hermits crawled on top of it. the toadstool polyps located on top, retracted quickly. the polyps on the perimeter were out and unphased. I watched the blue leg and it looked like he was just picking at "something" but not exactly the polyps. he stayed on there for about 10-15 seconds, before he walked off and went back to the sand.

I thought about yanking those blue legs and throwing them in the sump but I don't know if they're the problem.

out of all the hermits I bought (red scarlet and blue leg), I am down to 2 blue leg hermits. I might have one or two reds, but don't believe so. these blues have killed most of my snails off and took their shells.

my other question is, would my tank suffer if I were to pull all crabs out (and keep them in the sump), and only keep snails in the display tank? Not sure what other reef safe cleaners there are other than snails and hermits.

I pulled every single crab more than 6 years ago now.

Single best choice I’ve made.

No mystery death. No snail replacement. No coral losses.

When I did have them they did nothing but sit and wait for fish feeding time.

IMM….just trouble.

 

[reef tank 2.0]

well, snails typically eat algae, right? if you remove the crabs from your DT, what critters could you replace crabs with that will pick up the leftover food that end up on the sand/rocks? I might be overthinking that, but you need something, don't you?

 

[reef tank 2.0]

I probably changed too much at once, so I won't be able to tell for sure what fixed the problem, if it does.

double checked my gyre settings. It looks like I had that set at 60%. had it running for 6 seconds in each direction. I decided to set the pump at 30% and have it running for 4 seconds in each direction. hoping if it is the flow that's the problem, I decreased it. hopefully that doesn't upset the rest of the coral. I did notice the fish seem to be acting different;y. once I lessened the flow and time....they are moving around more freely. especially the clowns. behavior definitely changed. the more I look at it, I think the flow might be to low. the Stylo isn't flowing like it was. i'll keep an eye on it as days go on. fish are happy tho :beaming-face-with-smiling-eyes:

I moved my remaining 4 hermits to the stock tank (sump). there's quite a bit f rock in there, so hopefully they'll be fine.

my tank is rather clean, as well as my rocks. as I mentioned before, this tank is not that big. but I cannot find this emerald crab (if he's still alive). i'll continue to look, but I think he's innocent in all this. (Cause he's dead!!)

 

[VintageReefer]

I’m considering rehoming to the sump…

 

[reef tank 2.0]

emerald crabs are so cool looking. why can't they just be peaceful creatures