Cuc That Won't Get Eaten?

[Donya]

I feel a bit silly asking this because it's probably a lost cause, but I was hopping y'all would have some ideas that have escaped me. I'm looking for some sort of a CUC animal that won't become lunch for the gulf coast critters in my newest 20g: some large hermits and a small swimming crab. Info I'd read previously suggested they'd be a CUC in themselves, but as I've seen that's rather incorrect. The Clibanarius vittatus hermits are neither reef safe nor safe with much of anything as they are preferentially carnivorous/predatory and very destructive in general (the folks who mentioned having these as juveniles should be careful as they grow - they're fascinating animals, but are a hazard to many other commonly kept critters). When I feed them, it's like a food bomb gets set off in the tank. It leaves mess everywhere that isn't getting cleaned up effectively. The amphipods and worms that would have handled that were snack food for the hermits and the small swimming crab...which also has the habit of making food stashes that the hermits can't get to, and those turn into something awful if I don't find them fast enough. The fact that the food stashes aren't getting eaten by other things tells me again that there's not much else in the tank janitor-wise. I do WCs after every major feeding and the water is staying great, all non-food critters happy and thriving...but I'd really like something in there to clean up the scraps that are hard for me to get to and being ignored by the hermits & crab.

So...is there a good janitor out there that wouldn't become a snack for large hermits or a small crab (quarter-sized currently)?

If I get desperate, I could put some bristleworms in, but they will also be snack food eventually (would need to resupply periodically) and I had really hoped to keep them out of future tanks because of how big a pest they are in my 12g. I may end up doing that eventually anyway, because the hermit/crab diets & behavior rule out the most snails I'm familiar with and all other hermits. I know similar problems are faced in predatory fish tanks, so I was hoping there would be a non-bristleworm solution. If not...that's just life I guess. The mess is worth it to watch the madness that goes on in there. I just wanted to pick some brains on the forum first to see if I was missing something obvious.

 

[n3ont3tra]

Urchins?

 

[Lynden]

... would get annihilated.

My large Dardanus megistos typically left things alone if he was well-fed. You could try whelks (such as Nassarius); these live alongside my benthic trigger and avoid predation. Really bristleworms are your best bet. In what way were they a pest?

 

[Donya]

Nassarius are just small enough and slow enough when flipped out of the sand that I'd worry about them being had by the swimming crab, which will prey on small snails. On the other hand, larger snails too big for the crab to take would become appealing to the hermits because of the shells. I had wondered about Bumblebee snails because they would have a better defense shape-wise against the crab, but my recollection is that they prefer to prey on other inverts rather than doing janitor work and therefore wouldn't do the job needed.

In what way were they a pest?

The particular species I have is quite aggressive. I've been bitten quite a few times (properly bitten - not stung by the spines, which has happened as well but wasn't as bad) and they just get everywhere and on everything I need to pick up. I could wear gloves, but for dealing with little fiddly things in the tank it's awkward. They might also harass the encrusting bivalves in the tank unless I could find a way to get them higher off the sand.

 

[SkiFletch]

Well I have in the past seen some BIG nassarius snails. Happen to have one in my own tank. Guy's about 1.5" in shell length, perhaps some that size would be suitable

 

[Donya]

1.5" is about the size of a couple that I've got in my 12g, which still strikes me as being on the small side The main issue I see with Nassarius is that when I flick the ones I've got out of the substrate, their response isn't to close up, which is what they'd have to do to avoid being attacked by the swimming crab. Instead they reach further out of their shells and wiggle around slowly to turn over. That behavior would make a Nassarius of any size an easy snack for the crab or at least put the snails at risk of pretty bad injury. That crab moves extremely fast.

 

[Donya]

I think Nassarius of any size are ruled out now. Evil Mr. swimming crab just shed again after a few days of hiding and is double his previous size with big beefy arms now. If he keeps growing at this rate (~double size every few weeks) he'll be able to open any CUC snails like a soda can in no time. Better to play it safe and not give him expensive snacks, so I guess bristleworms it is... at least they're free snacks.

 

[n3ont3tra]

You've got to post some pics.

 

[nanocubeking]

If i'm right on a swimming crab its probably a blue crab. They will eat any thing anything!!!!!!!And same as a large hermit but how large is it over 2 inches he could get a fish.They best thing i can say is take they to the lfs and say they hitchhiked. They arent doing and wont do any good. Those kind of animals eat dead/dieing foods (in other words meaty stuff). It will be a last resort for them to eat algae. But best of luck to you.

 

[Donya]

You've got to post some pics.

Will do as soon as I can get my camera ready

If i'm right on a swimming crab its probably a blue crab. They will eat any thing anything!!!!!!!And same as a large hermit but how large is it over 2 inches he could get a fish.They best thing i can say is take they to the lfs and say they hitchhiked. They arent doing and wont do any good. Those kind of animals eat dead/dieing foods (in other words meaty stuff). It will be a last resort for them to eat algae. But best of luck to you.

Fortunately there are two things that make the situation ok so far: the tank is pretty much devoid of anything the crab could damage right now and it's also not a blue crab. Blue crabs were at the collection site too, but I deliberately left them alone because I know they get gigantic and collection of blue crabs was prohibited at that time of year. I'm pretty sure the little monster in my tank is an Ovalipes ocellatus, for which the common name is "lady crab." Swimming crabs include quite a few similar species, but lady crabs are about like mythrax, getting a carapace of ~4" max. The blue crabs stayed out of the tide pools where the lady crabs and Clibanarius vittatus preferred to be; from everything I saw at the site, those two species along with the strange encrusting bivalves all coexist peacefully in confined spaces. The stocking list right now is basically what was sitting together nonaggressively in the tide pools.

As far as diet goes, I've seen the crab eat about 50% dried seaweed preferentially, so the diets between blue and lady crabs is definitely different. For safety with other animals, the vittatus hermits are no better canidates for a normal aquarium than the lady crab. The hermits are by far the most destructive of the two species and I have no doubt they'd have a snack on fish/corals/etc. given the opportunity. It's the epitome of the non-reef-safe tank.

 

[Donya]

Pics as requested...stuck 'em in a tank photos thread:

http/www.fishforums.net/index.php?showtopic=230254

 

[Donya]

BLAST. Well, so much for having a nice happy gulf coast tank. The swimming crab is going through a phase now that I can only describe as it having constant crab tantrums. Every time it gets hungry, which is about about every couple of hours, it goes on a rampage. It doesn't kill stuff, but just has these frustration fits of running around the tank waving its arms & stuff. I was sitting by the tank watching TV the other day and it was having a go at me through the glass. I left the room, came back, and found it beating on the largest hermit's shell (not the hermit itself fortunately), so he got the boot out of the gulf coast tank. I now have a nice happy gulf coast tank and an angry crab tank...one more space hog I didn't realy need in my apartment, but oh well. I'm upgrading pumps anyway so I have the equipment handy. The crab is an amazing animal, but a real handful. It eats probably half its bodyweight in food each day and is still in the process of developing its adult behavior, like ambush hunting from the sand (so far it makes two piles of sand on its shoulders and thinks no one can see it better than it did before, but still a long ways to go). From what I've seen fo adult swimming crabs, they aren't completely nuts like this, so for the moment I'm guessing this is some behavioral phase associated with the transition from baby crab to sub-adult. I can understand why these crabs aren't too popular in the aquarium trade

This opens up the possibilities quite a bit more for the hermit tank as far as CUC goes. I will be trying out some Nassarius soon with the hermits since the swimming crab was the only risk there. I've never had issues between my large (~1.5-2") zebra-ish hermit going after my mine urchin. Was the remark about urchins getting ripped apart to do with the C. vittatus hermits or the swimming crab? Or both?

(edited to try to remove some amazing typos)