Pistol shrimp killing everything?!

[Reefing Qs]

 I don't like these old threads bad information. Yes japanese red pistols are a threat, but even big tiger pistol shrimp are nearly blind scavengers who are barely able to collect floating meat from the water column much less kill a healthy free swimming fish. They will scavenge a fish corpse in a second though, and I'd suspect 99 times out of 100 when you hear someone describing a tiger pistol that killed their fish they're describing a tiger that ate a dead or dying fish as that's one of their staple diets in the wild.

Can I get some clarification on this? I found this thread today as I am somewhat convinced my (red) Japanese Pistol Shrimp has been attacking my fish while they sleep for months. He's getting big enough to cause damage and I am worried he'll kill something soon.

Do they actively hunt fish? Are more defensive fish like clowns or tangs safe or should I just trade him in?

 

[Katrina71]

Can I get some clarification on this? I found this thread today as I am somewhat convinced my (red) Japanese Pistol Shrimp has been attacking my fish while they sleep for months. He's getting big enough to cause damage and I am worried he'll kill something soon.

Do they actively hunt fish? Are more defensive fish like clowns or tangs safe or should I just trade him in?

I have a blue legged pistol that kills anything he can catch sleeping. I saw it with my own eyes.

 

[Katrina71]

If you are concerned, and can catch him, I'd sump him. Jmo

 

[Reefing Qs]

For reference, https://www.liveaquaria.com/product/2129/?pcatid=2129 this is the one I've got. Their reference photo is near identical to my specimen. Live Aquaria seems fairly certain of themselves that they won't harm anything!

If you are concerned, and can catch him, I'd sump him. Jmo

I think it may come to this. I may move him to a separate tank with my clowns that cuddle in their nem all night.

A photo of one of the wounds I believe he caused:

 

[Cthulukelele]

Can I get some clarification on this? I found this thread today as I am somewhat convinced my (red) Japanese Pistol Shrimp has been attacking my fish while they sleep for months. He's getting big enough to cause damage and I am worried he'll kill something soon.

Do they actively hunt fish? Are more defensive fish like clowns or tangs safe or should I just trade him in?

Red Japanese pistols can and do kill shrimp and rarely but sometimes fish. They're much more aggressive and not a goby pairing shrimp. Tiger pistols are much much less dangerous. I'd never suggest a Japanese red for a reef tank. Sorry I realize my comment was confusing was commenting on the earlier posts in this thread about tiger pistols

 

[JayM]

If this is the shrimp you’ve got - it’s highly unlikely to be killing anything.

 

[JayM]

For reference, https://www.liveaquaria.com/product/2129/?pcatid=2129 this is the one I've got. Their reference photo is near identical to my specimen. Live Aquaria seems fairly certain of themselves that they won't harm anything!

I think it may come to this. I may move him to a separate tank with my clowns that cuddle in their nem all night.

A photo of one of the wounds I believe he caused:

I’m certainly not an expert on fish disease, but that looks a bit like uronema.

 

[Cthulukelele]

For reference, https://www.liveaquaria.com/product/2129/?pcatid=2129 this is the one I've got. Their reference photo is near identical to my specimen. Live Aquaria seems fairly certain of themselves that they won't harm anything!

I think it may come to this. I may move him to a separate tank with my clowns that cuddle in their nem all night.

A photo of one of the wounds I believe he caused:

Also it's possible those wounds were caused by a pistol shrimp. The 3 things I'd guess for wounds like that would be the pistol (if it's a Japanese red and not a tiger), a hermit, or a rock darting injury.

I second Jay though that if this fish was recently added that looks a lot like uronema

 

[Reefing Qs]

I’m certainly not an expert on fish disease, but that looks a bit like uronema.

That was a while ago, the firefish has since recovered without any intervention. It's a bit hard to see in the picture, but the red line was a scratch and there's a tiny circle of fish missing (like where the claws met).

My aurora goby found out he isn't a goby-pairing shrimp the hard way. He now lives in a separate burrow of his own!

 

[Idech]

I’m 99.9% certain my tiger pistol shrimp has killed hermit crabs and snails.

 

[Reefing Qs]

Also it's possible those wounds were caused by a pistol shrimp. The 3 things I'd guess for wounds like that would be the pistol (if it's a Japanese red and not a tiger), a hermit, or a rock darting injury.

I second Jay though that if this fish was recently added that looks a lot like uronema

I am fairly convinced at this point he's the culprit. The injuries I find on my fish are always in the morning and similar to the photo I shared, or a "V" shaped chunk taken out of a fin. The fish display no aggression even during feeding, they generally all scare each other. I hear the shrimp's snaps start shortly after lights-out and they don't stop.

Bangaii Cardinal
Aurora Goby
Red Firefish
Yellow & Purple Wrasse (Halichoeres leucoxanthus)

 

[Cthulukelele]

I’m 99.9% certain my tiger pistol shrimp has killed hermit crabs and snails.

Hermits who venture too close and small snails can fall victim (rarely imo), but usually if they do die the tiger loves to immediately scavenge their shell to help make a more structurally sound cave entrance so imo they're probably blamed for more deaths than they cause. A lot of times when they grab fallen snails and closed up hermits and drag them to the burrow they're trying to use those shells to build and they're almost completely blind so they don't realize something is in them

 

[Cthulukelele]

I am fairly convinced at this point he's the culprit. The injuries I find on my fish are always in the morning and similar to the photo I shared, or a "V" shaped chunk taken out of a fin. The fish display no aggression even during feeding, they generally all scare each other. I hear the shrimp's snaps start shortly after lights-out and they don't stop.

Bangaii Cardinal
Aurora Goby
Red Firefish
Yellow & Purple Wrasse (Halichoeres leucoxanthus)

Like I said red Japanese pistols are big and mean and even if it didn't do it I'd suggest getting it out of a tank with those docile fish.

 

[Reefing Qs]

Like I said red Japanese pistols are big and mean and even if it didn't do it I'd suggest getting it out of a tank with those docile fish.

Thanks, and agreed - I got him as a juvenile May 2022 and he's grown quite a bit and got more bold/mean with time - he completely comes out of his burrow during feeding time (100% lights on) to blindly chase mysis around.

The day he went in:

I may put him in the clown's tank to see how they fare before bringing him back to the store. He's got personality, just not a nice one. We'll see how much of the tank I need to tear apart to get his booking photo.

 

[Idech]

Hermits who venture too close and small snails can fall victim (rarely imo), but usually if they do die the tiger loves to immediately scavenge their shell to help make a more structurally sound cave entrance so imo they're probably blamed for more deaths than they cause. A lot of times when they grab fallen snails and closed up hermits and drag them to the burrow they're trying to use those shells to build and they're almost completely blind so they don't realize something is in them

I believe they can at least see light. Whenever I flash even a little bit of light on mine, it retreats in its cave.

I’ve often read about them using the shells or crabs and snails, but you can hear mine shooting its pistol many many times in a row when it kills. I had 15 hermits, down to 1, maybe 2.

 

[ISpeakForTheSeas]

To clarify here, the genus Alpheus that pistol shrimps come from has some debate going about if it should be one genus or be split into three at the moment.

It's possible that some of the species (likely ones that would be put into a separate genus than the goby-pairing species if the genus were split into three) are more predatory hunters (which would probably prefer only hunting pods and the smallest of fish and inverts), but by all accounts I can find, the goby-pairing ones seem to be almost entirely defensive/territorial rather than aggressive/predatory - the goby-pairing ones seem to be omnivorous scavengers. The only evidence of "predation" I've seen involved a cleaner shrimp harassing the pistol shrimp at the end of the pistol shrimp's burrow. In fact, I've heard of multiple cases of the goby bringing the shrimp a small snail or hermit, the shrimp bringing it inside, and the snail/hermit crawling out of the burrow unharmed later.

Despite common belief (which has been parroted numerous times even in scientific literature), these shrimp are not blind - in fact, they seem to have pretty good eyesight from the few studies conducted (though there is debate about if they can see red light or not).

For references and more discoveries on the matter, see the quotes below:

As stated, these guys really aren't the vicious hunters they're made out to be.

They're actually omnivores (see the quote below), and the tiger pistol (Alpehus bellulus) is one of two species so far (Alpheus randalli being the other - see the link in the quote below) that has been confirmed to feed on its goby partner's feces,* so adding a goby may very well help on the off-chance that your shrimp actually is being aggressive:

A quick note here on pistol shrimp diet - pistol shrimp do not seem to be predatory, rather they seem to be more opportunistic, omnivorous scavengers (the only "hunting" that seems to take place outside of the burrow is done by the gobies, not the shrimp, and - to my knowledge - no one has ever confirmed if the shrimp actually eat the "prey" brought to them by the gobies; it might be that the goby eats them rather than the shrimp, or the shrimp might eat them as people generally assume):

Goby and shrimp associations: more than meets the eye - Coral Reefs

link.springer.com

Some more info from the article linked in the quote above:

"Diet analyses of shrimp associates indicate copepods, interstitial matter, and seagrass as main food items. Incidental observations revealed a more varied diet, facilitated by goby associates. Cryptocentrus cinctus and C. singapurensis [= C. leptocephalus] were previously reported to introduce items such as algae and bivalves into burrows for associate shrimps. We observed the goby, Amblyeleotris latifasciata, capturing a small crab near the burrow entrance and carrying this prey item toward the burrow entrance. Upon arrival, it rapidly moved up and down, a characteristic behavior we can best describe as ‘jumping’. The shrimp emerged from the burrow and proceeded to remove the entire prey item from the mouth of the goby, without resistance or struggle from the latter, before retreating into the burrow (Fig. 1)."

Additionally, as noted in the article linked above, at least some Alpheus spp. clean their gobies by eating the parasites off of them.

*Source:

https://www.researchgate.net/publication/312094089_A_novel_aspect_of_goby-shrimp_symbiosis_gobies_provide_droppings_in_their_burrows_as_vital_food_for_their_partner_shrimps

Is anyone here actually aware of a case (preferably confirmed by video and/or scientific study) of a goby-paired pistol shrimp (or even one not paired) actively hunting? Because the only confirmed case I can find at the moment is one of an apparently unpaired pistol shrimp killing a cleaner shrimp that came right up to the front of the pistol's burrow.

Between the fact that I can't find any verifiable evidence of these shrimp actively hunting and the fact that their primary diet is thought (with at least one study's worth of supporting evidence) to be their goby partner's feces*, I'm strongly inclined to believe that these shrimp basically go out of their way not to kill most things (but they will defend their territory - i.e. their burrow). So, personally - unless someone has verifiable information that says otherwise - I would guess the odds of a pistol shrimp taking out two fish (including one that is relatively large) while they are not actively encroaching on it's burrow and while it has access to it's primary food source are extremely low. That's not to say it couldn't happen, just that it seems incredibly unlikely.

*Here's the link to the study referenced above:

https://www.researchgate.net/publication/312094089_A_novel_aspect_of_goby-shrimp_symbiosis_gobies_provide_droppings_in_their_burrows_as_vital_food_for_their_partner_shrimps

Them not being paired is one of the few reasons I could see for them potentially hunting, but if that were the case here, I would expect to see some damage to the fish from the shrimp feeding (or attempting to feed) on it. Given how most animals I’m aware weigh the risks of a hunt, I can’t imagine a pistol shrimp lacking its primary food source going after a large and potentially dangerous fish to just not eat it (very few animals hunt for sport in my experience).

Personally, I’d guess there’s something else at play here - internal parasites, something off with the water quality, electricity in the water column, etc. In most cases, stuff like that would seem way more likely to me than a rogue pistol shrimp hunting potentially deadly prey for the thrill of it.

Yeah, they're definitely not blind - there is some dispute about how good their eyes actually are, but the few studies I can find would seem to indicate to me that their eyesight is actually quite good (though there's some speculation that they may not be able to see red light).

A snapping shrimp has the fastest vision of any aquatic animal

Animals use their sensory systems to sample information from their environments. The physiological properties of sensory systems differ, leading animals to perceive their environments in different ways. For example, eyes have different temporal sampling ...

www.ncbi.nlm.nih.gov

https://www.researchgate.net/publication/262088563_Visual_acuity_of_the_goby-associated_shrimp_Alpheus_rapax_Fabricius_1798_Decapoda_Alpheidae

Edit: Another fun snippet about their diet:

Pistol shrimp are known to gather and eat macroalgae and seagrasses on occasion - the OP on the thread below caught their pistol doing this on video:

Repetitive clicking from Aquarium? SOLVED

Hey yall i thought i would share a fun little bit on my Monday. Started lastnight around dinner time. Click click click click, almost rhythmically. So i assumed a pump, mp10 somthing. Clean pump, clean mp10, clean skimmer About to go to bed, again clicking. Happening almost evey 5 minutes or...

www.reef2reef.com

 

[Cthulukelele]

I believe they can at least see light. Whenever I flash even a little bit of light on mine, it retreats in its cave.

I’ve often read about them using the shells or crabs and snails, but you can hear mine shooting its pistol many many times in a row when it kills. I had 15 hermits, down to 1, maybe 2.

I definitely don't want to invalidate your experience. A fully grown tiger pistol is entirely capable of taking down very small hermits and the occasional small/weakened snail. I'd hesitate to blame it all on the shrimp though. In my experience the biggest murderer of hermits are other hermits especially in the first 5 months or so before they establish turf. Also they tend to disappear. I haven't added blue legs to my tank in 5 years. Thought they all died years ago. Yesterday apropos of nothing I saw 7 or 8 blue legs out at meal time as my nutrients have been lower than usual and they were hungry

 

[Cthulukelele]

Thank you for the

To clarify here, the genus Alpheus that pistol shrimps come from has some debate going about if it should be one genus or be split into three at the moment.

It's possible that some of the species (likely ones that would be put into a separate genus than the goby-pairing species if the genus were split into three) are more predatory hunters (which would probably prefer only hunting pods and the smallest of fish and inverts), but by all accounts I can find, the goby-pairing ones seem to be almost entirely defensive/territorial rather than aggressive/predatory - the goby-pairing ones seem to be omnivorous scavengers. The only evidence of "predation" I've seen involved a cleaner shrimp harassing the pistol shrimp at the end of the pistol shrimp's burrow. In fact, I've heard of multiple cases of the goby bringing the shrimp a small snail or hermit, the shrimp bringing it inside, and the snail/hermit crawling out of the burrow unharmed later.

Despite common belief (which has been parroted numerous times even in scientific literature), these shrimp are not blind - in fact, they seem to have pretty good eyesight from the few studies conducted (though there is debate about if they can see red light or not).

For references and more discoveries on the matter, see the quotes below:

insight about their eyesight! I feel bad for propagating outdated info

 

[Katrina71]

Looks like a Red Sith Sump Lord to me

 

[ISpeakForTheSeas]

Thank you for the

insight about their eyesight! I feel bad for propagating outdated info

It's totally understandable- as I mentioned, I saw that info repeated a number of times in different articles. It was just when I went looking into it that I found that seems to be a myth that popped up somehow (I've found a few similar myths with other critters too).