Crab ID

[LaloJ]

I found this crab a while ago in my tank, sometimes my maroon clownfish wakes up with broken or torn fins and I suspect that the culprit may be this guy, I have no idea what species it is and I have no idea if it's aggressive but it always wanders around the sand and goes for the food along with the fish.

 

[ISpeakForTheSeas]

Any chance you can get a top-down, straight-on pic of the crab's back (showing the full back and legs) and a straight-on shot of the face and claws? (Preferably with both under somewhat brighter white light).

 

[LaloJ]

Any chance you can get a top-down, straight-on pic of the crab's back (showing the full back and legs) and a straight-on shot of the face and claws? (Preferably with both under somewhat brighter white light).

I'm going to try to take a photo of him from above, or I may have another photo where he looks better but he was smaller, the guy has grown.

 

[LaloJ]

Well this seems to be a joke in very bad taste knowing that just today when I wanted to clear up this doubt my clownfish literally disappeared from the tank, I looked for it everywhere and coincidentally the crab disappeared too, with this it was obvious that it was involved in something bad, and finally a few minutes ago I just saw him coming out of his hiding place with half of the clownfish already eaten, dang it I feel very bad for this fish since I let a lot of time pass, but just today I wanted to dispel the doubt and this happens, very bad lucky IMO .

 

[LaloJ]

I was able to get this photo of the aggressor, he still hasn't come out of hiding, could you give an idea about his identification?

 

[ISpeakForTheSeas]

I was able to get this photo of the aggressor, he still hasn't come out of hiding, could you give an idea about his identification?

It leads me to thinking that it could be either from the Grapsoidea superfamily or the Xanthidae family; but I can't tell for sure.

The shape of the crab's shell and the size/shape of the face and claws can really help with narrowing down the kind of crab; the coloration, patterns, and texture of the crab can help find specific species - or sometimes genera - from there.

 

[LaloJ]

It leads me to thinking that it could be either from the Grapsoidea superfamily or the Xanthidae family; but I can't tell for sure.

The shape of the crab's shell and the size/shape of the face and claws can really help with narrowing down the kind of crab; the coloration, patterns, and texture of the crab can help find specific species - or sometimes genera - from there.

Thanks, to be honest I had never read about a case where a crab killed a fish in a tank, I knew about anemones and predatory fish but not about crabs, what a way to learn it.

 

[ISpeakForTheSeas]

Thanks, to be honest I had never read about a case where a crab killed a fish in a tank, I knew about anemones and predatory fish but not about crabs, what a way to learn it.

Yeah, it's unfortunate but this is a big part of why only a handful of crab species (emeralds, pitho, porcelain, Acro, pom pom, etc.) are sold regularly in the hobby - most other crabs have been known to eat corals, and some (especially bigger species) have been known to kill fish when given the chance.

 

[Katrina71]

Don't beat yourself up. Crabs are very good at hiding. I had a gorilla crab for over a year and didn't know it. I'm sorry for the loss of your fish, but the crab was just doing what they do. He would make an excellent addition to a sump.

 

[Lavey29]

Not sure what species it is but doubt he killed a live swimming clown fish. He may have attacked a weak unable to swim or already dead fish in the tank. Is it possible your clown was getting aggression from another fish and got injured then the crab took advantage?

 

[ISpeakForTheSeas]

Not sure what species it is but doubt he killed a live swimming clown fish. He may have attacked a weak unable to swim or already dead fish in the tank. Is it possible your clown was getting aggression from another fish and got injured then the crab took advantage?

This is a good point - I would seriously consider if the clown could have been weakened/killed by something else first (disease, aggression, etc.) or otherwise particularly vulnerable for some reason.

 

[LaloJ]

I don't think that was the case, from what I see the clown slept near the crab hiding place, I never knew what his hiding place was until now, but I'm sure that the clown slept there, the clown was an active fish that ate and It swam very well, and it wasn't being bothered by any other fish, it was just with a blue damsel which is quite peaceful actually.

 

[Tired]

How big is the crab, and how big was the clownfish? They do scavenge and go after dying animals.

 

[LaloJ]

The crab is smaller than the clownfish, the clownfish is a couple of inches, maybe 6cm, the crab is 1 or maybe 1.5cm smaller. I fed the clownfish at night before his died with mysis and seafood porridge as I normally do and he ate like a glutton, he had no signs of illness, he ate very well and was a fat fish. However, he always slept in the same place, near the crab's hiding place.

 

[Tired]

I somewhat doubt the crab could have killed a fish that much larger than it. A freak incident like a heart attack or ruptured aneurysm is always a possibility with mystery deaths.

Seafood porridge?