Hermits and Emerald Dying Off - Conch Missing

[bzb]

Not sure what's going on here, looking for ideas before I run out and get more.

I've been dealing with a bit of a slime/fuzz algae bloom for the last couple weeks. No one has been able to identify for sure. I'm not dosing anything and not running GFO yet, but have cut back a bit on the feeding and looking into other inverts. I recently acquired a sea hare who is a workhorse.

I've been missing my conch for the entire time I've seen the algae bloom. I haven't gone so far as digging up the sand, but I've poked around with my grabber to see if I can find his shell. I've read that they sometimes hibernate, so I haven't been too concerned.

Over the same time period, I've seen hermit crab bodies laying about - probably around 5 or 6. Again, figured they might be molts, but they seem too... meaty...

This morning, I finally found my large emerald crab. Again, thought it may be a molt, but it's not. And the shell was absolutely covered in this slime/fuzz algae.

I tested for Copper with Hanna checker on both tank and the RODI. Straight zeroes.

pH: 7.8
Temp: 78
SG: 1.025
Alk: 8.4 (Hanna)
Ca: 440 (Salifert)
Mg: 1188 (Aquaforest)
Nitrate: 0 (Giesemann ULR)
Phos: 0.17 (Hanna)

Fish are fine and eating well. Corals are all fully opened with the exception of the hammer coral, which isn't fully extended. Only major change was giving away a large xenia rock last weekend - but this has been going on for a while before that.

Any guesses?

 

[lmm1967]

Mg: 1188 (Aquaforest). - raise that to over 1300

 

[ActiveAngel]

Mg: 1188 (Aquaforest). - raise that to over 1300

I agree, but I don’t believe this would cause any potential die-offs.

Did you introduce any live-rock at any point? Or did you use exclusively dry rock that you seeded? I’m suspicious if you have a pest that could be chowing down on various inverts.

 

[raz0945]

It's unusual for a system that has been up for a while to have "0" nitrates, can you get a friend to retest nitrates for you? How often and what % do you do on water changes.

 

[ActiveAngel]

It's unusual for a system that has been up for a while to have "0" nitrates, can you get a friend to retest nitrates for you? How often and what % do you do on water changes.

I support double checking with a friend. However, my systems often have 0 nitrates (or at least, under testable levels of 0.25ppm), so I’d believe it... but it never hurts to double check.

 

[bzb]

Mg: 1188 (Aquaforest). - raise that to over 1300

Been following the BRS method of dosing Mg at the end of the CA/Alk jugs. I'm about halfway through those. Think I should just do a small dose to raise it? That caused massive swings the last time I screwed around with Mg.

I agree, but I don’t believe this would cause any potential die-offs.

Did you introduce any live-rock at any point? Or did you use exclusively dry rock that you seeded? I’m suspicious if you have a pest that could be chowing down on various inverts.

The xenia rock was the only significant sized one (now with @aestheticlibra) which I got way back in September. Any other frags on rocks are pretty small. I thought about that - but this is a pretty recent phenomenon. The emerald crab was intact, just toast.

It's unusual for a system that has been up for a while to have "0" nitrates, can you get a friend to retest nitrates for you? How often and what % do you do on water changes.

I was dosing nitrates but stopped in Feb. It's back to undetectable, and I'm fairly confident on it because I can raise it with the dosing liquid and get it to a few ppm on same day, but gets consumed down to undetectable within a day or two max. I test with Salifert (Low Range) and Giesemann (ULR) and both are undetectable.

I assume my phosphate levels are from the heavy frozen feedings, and a good amount of nori. I've reduced that a bit (poor fishies).

I pull out about a baseball size of chaeto every two weeks. The skimmer runs fairly dry and I get about a cup of dark skimmate every week.

Weekly 6% water change.

 

[ActiveAngel]

I purchased my first tank used, complete with live rock, sand, and corals, where it was previously running with no additions for almost 30 years. After which, I had it for an additional two years, with no rock additions, when I discovered a large bobbit worm. It was hiding inside the rocks, and at night coming out to attack inverts and nibble nearby corals.

if that huge sucker could hide for a couple decades, I wouldn’t be surprised if something else, maybe even something small, could hide for six months. Just saying… It’s a reasonable possibility.

 

[bzb]

Well that's no bueno. So then, nothing I can really do except just keep adding and hoping?

 

[bigd]

I know I’ve had some molts that I just knew was the dead crab only to find it roaming around a few days later. Seeing as how you’ve got several though, may not be the case. I‘ve found several molts over the last few weeks in my tank. Not sure what triggers them, if anything, other than growth.

 

[bzb]

I know I’ve had some molts that I just knew was the dead crab only to find it roaming around a few days later. Seeing as how you’ve got several though, may not be the case. I‘ve found several molts over the last few weeks in my tank. Not sure what triggers them, if anything, other than growth.

Here's to hoping. The emerald crab was pretty much intact, but I'm not sure how they wiggle out of those shells and if they leave it as complete as this thing was. I'll keep looking for him.

Below is a pic of one of the hermit legs I found... looks kinda meaty on top to me.

Also that dark spot up above is the sea hare. He found a hole he likes, I guess.

 

[dball711]

Most likely molts.

 

[lmm1967]

that hermit crab pic is a molt

emeralds - pick it up, the top half and bottom half will separate like they are hinged if it's a molt

 

[bzb]

Nope, it's solid and tight together. Also, if I get aquatic coronavirus from this, you guys are never hearing the end of it.

 

[lmm1967]

Yeah - man, he looks dead, Not sure I would have touched that.















I'm kidding - I've grabbed them plenty of times - you're good and it's better to know for sure.

 

[bzb]

Not washing my crabby hands until I get to shake your hand at the next meeting

Also: picking up the sea hare was way more interesting. And likely I got crabs from him.

 

[raz0945]

It sounds like your doing it right, good luck! You could try going to 15 to 20 % water changes, it has work for some if you can't find the answer.

 

[kullas]

I looked in my tank this evening after reading this post and found 2 of my hermits out of ther shells. I picked them out and realised they were molts. Had me worried for a few minutes.

 

[FutureInterest]

Typically when crustaceans die in our reef systems it's a warning sign that you may have low iodine. They are otherwise pretty hardy and can tolerate wide parameter ranges. Iodine though is a critical component for molting and for their shells. I've seen your tank and you had that massive xenid in there... And they soak up iodine as well at a high rate. That xenid was so large it was like half of your tanks biomass... And could very well have been soaking up your available iodine.

I don't normally recommend dosing iodine without testing... But it sounds like adding a lil here in accordance with manufacturer directions is in order. For most of us just doing regular water changes will suffice to keep these levels where they need to be. I don't know when you last did a water change, but that certainly won't hurt.

 

[bzb]

Typically when crustaceans die in our reef systems it's a warning sign that you may have low iodine. They are otherwise pretty hardy and can tolerate wide parameter ranges. Iodine though is a critical component for molting and for their shells. I've seen your tank and you had that massive xenid in there... And they soak up iodine as well at a high rate. That xenid was so large it was like half of your tanks biomass... And could very well have been soaking up your available iodine.

I don't normally recommend dosing iodine without testing... But it sounds like adding a lil here in accordance with manufacturer directions is in order. For most of us just doing regular water changes will suffice to keep these levels where they need to be. I don't know when you last did a water change, but that certainly won't hurt.

Ahhh, good note! I'll see if I can find a calculator to get that bumped up.

Last water change I did was when I gave away the xenia rock. Kinda had to

 

[Eric_n_Ga]

Do you have a pistol shrimp ?