Sally light foot crab experience?

[GreatLakeReefer]

Hey reefers,

I don't see too many threads about the aggressiveness of sally light foot crabs but I'm in need of your personal experiences.

I committed the ultimate sin, and bought one without researching first.. While at my LFS, I discussed my past failure with an emerald crab (only lasted 2 weeks) with the owner of the shop and i was shown the sally light foot crab. They looked SOOO cool!! i was assured they were reef safe and would help with my GHA and other nuisance algae. I have a pistol shrimp with various hermits and snails.

Whelp now that its jumping all around my tank, i started googling.. and they apparently get aggressive.

Anyone have personal experience good or bad? Should i stop the panic? Or so i need to plan a trap and get it out???

 

[Subsea]

Hey reefers,

I don't see too many threads about the aggressiveness of sally light foot crabs but I'm in need of your personal experiences.

I committed the ultimate sin, and bought one without researching first.. While at my LFS, I discussed my past failure with an emerald crab (only lasted 2 weeks) with the owner of the shop and i was shown the sally light foot crab. They looked SOOO cool!! i was assured they were reef safe and would help with my GHA and other nuisance algae. I have a pistol shrimp with various hermits and snails.

Whelp now that its jumping all around my tank, i started googling.. and they apparently get aggressive.

Anyone have personal experience good or bad? Should i stop the panic? Or so i need to plan a trap and get it out???

I did not find them aggressive to fish or live stock.

Yes, I read what live.aquaria wrote and that was not my experience. Apparently, they don’t need to stay in the water, so mine dried up on the floor and I never replaced it. For certain, I have had emerald crabs go rouge.

 

[CHSUB]

Worst “reef safe” crab…absolute terror! Gets huge and lightning fast.

 

[Subsea]

Worst “reef safe” crab…absolute terror! Gets huge and lightning fast.

Definitely fast.

Apparently, I didn’t have mine long enough.

This is what Wikipedia says and note the last sentence with crabs picking ticks off iguana.

Ecology and behavior​

This crab lives among the rocks at the often turbulent, windy shore, just above the limit of the sea spray. It feeds on algae primarily, sometimes sampling other plant matter, sponges, mollusks (such as clams), crustaceans (including other crabs), fish, young sea turtles, bird eggs and droppings, bat guano and dead animals (mainly seals and birds).[4] As larvae, they feed on phytoplankton.[5] They have been known to resort to cannibalism when populations densities are high or food is scarce.[4] It is an agile crab, capable of leaping,[6] and consequently hard to catch. Not considered very edible by humans, it is used as bait by fishermen. It is preyed upon by the chain moray eel, Echidna catenata, as well as by octopuses.[7][8]

G. grapsus has been observed in an apparent cleaning symbiosis taking ticks from marine iguanas on the Galápagos Islands.[9

 

[CHSUB]

Definitely fast. Apparently, I didn’t have mine long enough.

This is what Wikipedia says and note the last sentence with crabs picking ticks off iguana.

Ecology and behavior​

This crab lives among the rocks at the often turbulent, windy shore, just above the limit of the sea spray. It feeds on algae primarily, sometimes sampling other plant matter, sponges, mollusks (such as clams), crustaceans (including other crabs), fish, young sea turtles, bird eggs and droppings, bat guano and dead animals (mainly seals and birds).[4] As larvae, they feed on phytoplankton.[5] They have been known to resort to cannibalism when populations densities are high or food is scarce.[4] It is an agile crab, capable of leaping,[6] and consequently hard to catch. Not considered very edible by humans, it is used as bait by fishermen. It is preyed upon by the chain moray eel, Echidna catenata, as well as by octopuses.[7][8]

G. grapsus has been observed in an apparent cleaning symbiosis taking ticks from marine iguanas on the Galápagos Islands.[9

I had one about 25 years ago in a 90 gallon. What started out as a cute little crab turned into an abomination. Got as big as my palm and so fast I could not believe it. Took months to remove. Never seen anything move so fast, almost like it floated over the rock. I only got it because it caught a Chromis while I was watching and it wouldn’t let go of the fish.

 

[dwest]

I’ve seen big ones on top of rocks near shorelines in the Caribbean. I wouldn’t want one in my tank, but they sure are cute when little.

 

[BZOFIQ]

They are not fully aquatic and need to come out of the water.

Not long lived because of the above mentioned requirement.

 

[Mark Goode]

There are two crabs which carry the name Sally Lightfoot; the flat brown & yellow one (percnon gibbesi or something), and the semi-aquatic one from the Galapagos islands. You probably have the former. I've had two over the years, and found them to be a delight. Great characters, great algae eaters, and always active. I saw no aggression at all. I've just decided to get another.

 

[Soren]

Hey reefers,

I don't see too many threads about the aggressiveness of sally light foot crabs but I'm in need of your personal experiences.

I committed the ultimate sin, and bought one without researching first.. While at my LFS, I discussed my past failure with an emerald crab (only lasted 2 weeks) with the owner of the shop and i was shown the sally light foot crab. They looked SOOO cool!! i was assured they were reef safe and would help with my GHA and other nuisance algae. I have a pistol shrimp with various hermits and snails.

Whelp now that its jumping all around my tank, i started googling.. and they apparently get aggressive.

Anyone have personal experience good or bad? Should i stop the panic? Or so i need to plan a trap and get it out???

Do you know what species of "Sally Lightfoot" crab you have? I think there are a few with this common name, and there is a wide range of variation in traits between different species of this name.

If you have a Percnon gibbesi which have been the most common available in my experience, I do not think you have much to worry about. I have had one in my 40g tank for about a year and it has not grown very quickly. It is nimble and active and will fend for itself against the curious fish, but I have not seen any aggression. According to data I can find on this species, it does not seem likely to get bigger than about 3-4" leg span with a carapace maximum diameter around 2" (which is not small, mind you, but not large enough to take down most fish).
This crab is so interesting to watch as it scurries around the tank and just keeps picking at algae non-stop. The coloration makes for a striking appearance with the different bands of brown, dark red, orange, and yellow.

I knew there was potential risk when I added this crab, but I wonder if some of the fear comes from the confusion over common name. Maybe my crab will become a terror in a few years; my experience is still pretty limited.

 

[GreatLakeReefer]

Hey reefers,

I don't see too many threads about the aggressiveness of sally light foot crabs but I'm in need of your personal experiences.

I committed the ultimate sin, and bought one without researching first.. While at my LFS, I discussed my past failure with an emerald crab (only lasted 2 weeks) with the owner of the shop and i was shown the sally light foot crab. They looked SOOO cool!! i was assured they were reef safe and would help with my GHA and other nuisance algae. I have a pistol shrimp with various hermits and snails.

Whelp now that its jumping all around my tank, i started googling.. and they apparently get aggressive.

Anyone have personal experience good or bad? Should i stop the panic? Or so i need to plan a trap and get it out???

I did not find them aggressive to fish or live stock.

Yes, I read what live.aquaria wrote and that was not my experience. Apparently, they don’t need to stay in the water, so mine dried up on the floor and I never replaced it. For certain, I have had emerald crabs go rouge.

Ok well I’m going to take that as encouraging. I plan on observing for a few weeks before getting aggressive myself and trying to evict it.

 

[GreatLakeReefer]

Hey reefers,

I don't see too many threads about the aggressiveness of sally light foot crabs but I'm in need of your personal experiences.

I committed the ultimate sin, and bought one without researching first.. While at my LFS, I discussed my past failure with an emerald crab (only lasted 2 weeks) with the owner of the shop and i was shown the sally light foot crab. They looked SOOO cool!! i was assured they were reef safe and would help with my GHA and other nuisance algae. I have a pistol shrimp with various hermits and snails.

Whelp now that its jumping all around my tank, i started googling.. and they apparently get aggressive.

Anyone have personal experience good or bad? Should i stop the panic? Or so i need to plan a trap and get it out???

Do you know what species of "Sally Lightfoot" crab you have? I think there are a few with this common name, and there is a wide range of variation in traits between different species of this name.

If you have a Percnon gibbesi which have been the most common available in my experience, I do not think you have much to worry about. I have had one in my 40g tank for about a year and it has not grown very quickly. It is nimble and active and will fend for itself against the curious fish, but I have not seen any aggression. According to data I can find on this species, it does not seem likely to get bigger than about 3-4" leg span with a carapace maximum diameter around 2" (which is not small, mind you, but not large enough to take down most fish).
This crab is so interesting to watch as it scurries around the tank and just keeps picking at algae non-stop. The coloration makes for a striking appearance with the different bands of brown, dark red, orange, and yellow.

I knew there was potential risk when I added this crab, but I wonder if some of the fear comes from the confusion over common name. Maybe my crab will become a terror in a few years; my experience is still pretty limited.

Thanks for this feedback. I’ll try to get a better ID. I’m gonna try not to jump to conclusions but glad to hear from some people who have actually had them in their tanks.

 

[Mark Goode]

Thanks for this feedback. I’ll try to get a better ID. I’m gonna try not to jump to conclusions but glad to hear from some people who have actually had them in their tanks.

These I had.

 

[GreatLakeReefer]

Worst “reef safe” crab…absolute terror! Gets huge and lightning fast.

what behavior did it start doing that made it terror?? i can see how fast they are

 

[CHSUB]

what behavior did it start doing that made it terror?? i can see how fast they are

Ate my fish!

 

[Mark Goode]

A percnon gibbesi? No, you must have had a different crab - or small fish. I can see no way a gibbesi can catch and kill a healthy fish, though like all crabs they'll eat a sick one. Though their maximum size is around four inches, around three of those inches are legs, their bodies are quite small and flat. They also have small claws- far too small to hold a struggling fish. What did your crab look like?

Willing to be corrected if I'm wrong though.

 

[CHSUB]

A percnon gibbesi? No, you must have had a different crab - or small fish. I can see no way a gibbesi can catch and kill a healthy fish, though like all crabs they'll eat a sick one. Though their maximum size is around four inches, around three of those inches are legs, their bodies are quite small and flat. They also have small claws- far too small to hold a struggling fish. What did your crab look like?

Willing to be corrected if I'm wrong though.

Healthy Chromis, ate a least 2. You posted a picture. Got very big….as soon as lights went out crab would start hunting.

 

[GreatLakeReefer]

what behavior did it start doing that made it terror?? i can see how fast they are

Ate my fish!

Ok yea that’s terrible!

 

[CHSUB]

Ok yea that’s terrible!

Haha!

 

[Soren]

Healthy Chromis, ate a least 2. You posted a picture. Got very big….as soon as lights went out crab would start hunting.

You are quite sure you had a Percnon gibbesi Sally Lightfoot crab? How big was yours? I do believe that these have the agility to try to catch a small fish, but mine seems too small to do any damage to all but the tiniest fish (like possibly a neon goby or smaller) even though it is probably at least 3" diameter across the legs (not too far from the maximum supposed length, from what I've read).

Like @Mark Goode , I also anecdotally am surprised by my experience to hear about yours if we have/had the same species and am genuinely curious if I need to be concerned about my crab as a hazard to my fish. I have mine housed with some yellowtail damselfish as the smallest fish in the aquarium.

 

[MadreeferNJ]

Had one that got quite large and very fast moving. I cannot prove it but think it killed fish during the night.