Crabs keep going missing!

[FishAndAquatics]

Hey there everyone. So, lately I've been having an issue with some of my crabs. I bought about 40 of these reef safe red burrowing crabs about a month ago and know how to properly take care of them and everything, but over the course of 2 weeks, I've lost 38 of them completely. I searched the sand bed, the rocks and can't find them. I read that when they die, they will float to the top of the tank, which some of them did, but the rest disappeared. I can't even find any of the shells or remains of the crabs. Anyone know what could be happening? I have a green pistol shrimp but I don't think he's killing and eating them. Does anyone have any answers? I have an orange shoulder tang, some clownfish, cleaner wrasse, conch, sand sifting starfish, feather starfish, some alleni neon damsels and a pistol shrimp. I have also noticed that 90% of my hermit crabs disappeared. Could this be the work of a mantis shrimp or something worse? :headwalls:

 

[Betta132]

I'm not familiar with that crab, but its body shape and stance makes me think it might actually be a land crab of some sort. There are many species of land crab that can survive underwater for some time, but will eventually die. In fact, what you have there looks a lot like a fiddler crab, so I googled "Female red fiddler crab" and came up with a bunch of crabs that look a whole lot like that one up there.
I'm about 98% positive that you have fiddler crabs. They're dying because they're a brackish water species that needs land to survive.

Also, a feather star? Do you mean a crinoid? Those are not at all suitable for aquariums, they eventually starve about 99% of the time.

 

[Sounds Fishy]

Hey there everyone. So, lately I've been having an issue with some of my crabs. I bought about 40 of these reef safe red burrowing crabs about a month ago and know how to properly take care of them and everything, but over the course of 2 weeks, I've lost 38 of them completely. I searched the sand bed, the rocks and can't find them. I read that when they die, they will float to the top of the tank, which some of them did, but the rest disappeared. I can't even find any of the shells or remains of the crabs. Anyone know what could be happening? I have a green pistol shrimp but I don't think he's killing and eating them. Does anyone have any answers? I have an orange shoulder tang, some clownfish, cleaner wrasse, conch, sand sifting starfish, feather starfish, some alleni neon damsels and a pistol shrimp. I have also noticed that 90% of my hermit crabs disappeared. Could this be the work of a mantis shrimp or something worse? :headwalls:

I think that your Pistol shrimp is responsible.There are a few videos on You Tube of Pistol shrimp eating crabs... I just Googled it.Does the Pistol Shrimp appear to be well fed?

 

[Bent]

Those are not gilled crabs brah. Look close at it the pic, they are branchiostegal lunged. They are drowning.

Whoever sold you those is either ignorant, or a downright dirty theif.

 

[Calappidae]

I think that your Pistol shrimp is responsible.There are a few videos on You Tube of Pistol shrimp eating crabs... I just Googled it.Does the Pistol Shrimp appear to be well fed?

This is news to me, I've never once seen evidence, video, or heard of pistol shrimp killing crabs. (Bar NatGeo, but a lot of their information has been called out on by real biologist. Several errors in their world's deadliest videos, with them being flat out false or overdramatized.)

Infact, pistol shrimp are some of the most passive available shrimp in the hobby, only firing for defense to scare predators, or call for a mate. Getting shot doesn't feel like anything. I think you're confusing yourself with smashing variations of mantis shrimp.

But I agree with Betta, they are uca sp. A semiaquatic species which requires land to come up for air. They've basically drowned in your tank.

 

[Betta132]

Pistol shrimp do not eat crabs unless the crabs are dead. They quite simply aren't strong enough to kill a crab. I've been shot by them, and it just stings a bit. It's about the same strength as a rubber band, judging by the feeling of it.

Those are some really pretty fiddlers. I highly suggest setting up a small tank for them, they don't need much space. What they really need is a tank that's about half land, preferably just wet sand, and half brackish-to-salt water.

 

[Shawn O]

Those are some really pretty fiddlers. I highly suggest setting up a small tank for them, they don't need much space. What they really need is a tank that's about half land, preferably just wet sand, and half brackish-to-salt water.

+1. A 20 long or a 40B would be good. Just pile the sand high as possible at one end and add saltwater. You could even add a floating dock of some sort.