Sally light foot crab experience?

[Grog]

While I love my inverts, crabs and shrimp in particular, this is one of those, 'it depends', things.

It can depend on what you have in your tank. If you have larger predators, the SLF will likely be food. If you have small fish, then the opposite may be true. They are aggressive predatory scavengers.

It can depend on how well it is fed. If you feed lightly and the crab is hungry, well, expect some unwanted behavior. If you feed heavy and/or hand feed the crab, it may never bother anything. But all that depends on the crab, its mood, its size, the season, etc.

All that said, I have no SLF in either of my current systems. I've had them in prior tanks and they weren't terrible, but not great. As folks indicated above, they didn't last long, a few months as best. SLF are mid-range with their aggression, but even so I'd not put them in most reef tanks. I never saw mine messing with coral, but they did disturb the peace and upset the other inhabitants. The risk to reward just wasn't there for me to add one into either tank.

The good news is if you want to remove it, then it should be easy. You can very likely go fishing for it with a piece of table shrimp on a string at lights out, and net the thing. I've done it many times, and it is kind of fun.

 

[mcarroll]

I committed the ultimate sin, and bought one without researching first..

...no, you just bought yourself a reason to get a morey or an octopus! Sweet!!!

It is preyed upon by the chain moray eel, Echidna catenata, as well as by octopuses.[7][8]

:) ;)

@GreatLakeReefer keep in mind that almost everyone buys these as CUC and doesn't feed them....in terms of crabs we like THIS IS A BIG ONE and would need a LOT of "food waste" to stay happy. I'm willing to write off most negative reports on this basis.

Hungy crabs cannot be trusted, but they CAN BE prevented. Keep him fed and I'm sure you'll (and he'll) be fine.

 

[CHSUB]

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.

It was absolutely the common Sally you see at lfs. Had it iirc about two years, the details are a little fuzzy being 25 years ago but the general consensus was never again. It killed a Chromis by pouncing on it near lights out and I was able to retrieve both the fish and crab together for removal to Biscayne Bay. Crab’s body was about half dollar sized and had been trying to remove for months.

For comparison, had an Arrow Crab do similar to a hippo tang but was able to save the hippo and remove the Arrow.

What isn’t fuzzy with details is both crabs ability to catch and kill healthy fish.

Both crabs are no go in reef tanks, imo and ime…..

 

[427HISS]

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

 

[Paul B]

Sally Lightfood crabs are very common on any tropical beach and are not sub marine crabs. They live most of their life out of water on the rocks eating algae.

Because of that, they will climb out of your tank if your rocks go near the surface.

I have had 3 or 4 of them do that so I can't keep them because my rocks go over the surface of my tank.

 

[Mark Goode]

Sally Lightfood crabs are very common on any tropical beach and are not sub marine crabs. They live most of their life out of water on the rocks eating algae.

Because of that, they will climb out of your tank if your rocks go near the surface.

I have had 3 or 4 of them do that so I can't keep them because my rocks go over the surface of my tank.

I think that's the other Sally Lightfoot, Grapsus grapsus. This from Google:

Percnon gibbesi (commonly known as the Sally Lightfoot or Nimble Spray Crab) is considered fully aquatic, though it belongs to a family of shore crabs that are technically capable of leaving the water.
In both the wild and home aquariums, you will almost never see them on land. Here is the breakdown of their lifestyle:

Habitat: They live primarily in the subtidal zone (usually 0 to 4 meters deep) among rocky crevices and boulders. Unlike other "shore crabs" that scavenge on dry rocks, P. gibbesi prefers to stay submerged to forage for algae and detritus.

Aquarium Life: In a tank, they do not require a "land" area or a basking spot. They spend 100% of their time underwater, scurrying over live rock.

They are often confused with Grapsus grapsus (the Pacific Sally Lightfoot). Grapsus grapsus is the one you see in nature documentaries jumping across dry rocks in the Galapagos; that species is semi-terrestrial. Percnon gibbesi is the flatter, faster version typically sold in the aquarium trade, and it stays in the water.

Note for keepers: Because they are "spray crabs," they are incredibly fast and agile. If your aquarium is open-top, they might occasionally crawl up to the waterline or even climb out by accident, so a secure lid is recommended

 

[Paul B]

I think that's the other Sally Lightfoot, Grapsus grapsus. This from Google:

I think Google is wrong on this one. I have seen hundreds of SallyLight foots in the Caribbean and at low tide, they are almost always out of the water. Never on dry land but just at the water line or on wet rocks.

They seem to be eating seaweed or some other growth on the rocks.
I'm sure moray eels hunt them just at the waters edge.

I have also seen any in the South Pacific. I didn't know they were separate species, but it makes sense