HCA: Hermit Crab Association

As the title implies, I'm trying to figure out what's going on. I'll give as much info as I can readily recall and answer any questions as best I can.

Eight months ago I set up a new tat for E's and bought 11 of them (all smalls) that were in two different pet stores and living in deplorable conditions (i.e. no sub, improper temp and humidity, commercial food, no salt water). All were obviously needing to molt. All of them dug in to molt within the first month or so and all but two survived. Not a bad result, all things considered.

Over the last six months, I've lost seven more crab. All went under and never came up. A recent deep cleaning revealed nothing more than seven empty shells and part of one corpse which suggested to me that perhaps I had underestimated how much these guys like to tunnel and that maybe I had overcrowded the tank. This was about two months ago. Today, I went looking for one of the remaining three crab that I haven't seen in over six weeks. Again, I found an empty shell, a soft corpse but no exo.

The 'Tat: 37 gallon bow front aquarium purchased new last December with a plastic top and UV-B lamp. Measurements are 30L x 12-16W x 18H. Tank was prepped by a cleaning with white vinegar and dechlorinated water before adding the substrate. Two coconut shells are currently in place as hides, there are plastic plants for color and climbing, a moss pit, cork wood and some cholla wood. All wood was baked before being placed into the tank. Dechlorinated fresh water is used for misting when needed. Heat is provided by an Ultratherm heater attached to the outside of the rear wall. Spare shells, both used and unused, and in several sizes are available although only two of them ever swapped shells. It's my understand this isn't uncommon for E's.

The Sub: Play sand from Lowe's, EE mixed at a ratio of one compressed block per 50lbs of sand, and dechlorinated salt water (Instant Ocean mixed per instructions). The sub is sand castle consistency and 9 inches deep. This is the same sub formula I use in my two tanks of PP's with no issues. I've never lost a PP.

Conditions: I have a calibrated ZooMed gauge mounted a few inches off the tat floor and the temp/humidity averages 85/80. They have a day and night cycle that roughly follows the natural sunlight pattern.

Food/water: Honey, freeze dried shrimp, shrimp, krill, blood worms, and meal worms with no preservatives or chemicals are offered and changed at a two day interval. Feeding and watering dishes are routinely washed in Dawn and thoroughly rinsed and dried before reusing. A cuttlebone and egg shells are available for calcium. Millet, scrambled eggs and veggies are offered two or three times a week. Sometimes I add organic nuts and dried berries as treats. This is the same feeding regimen I use for my PP's. Two bowls of water, fresh and salt, are available at all times and are deep enough to them to submerge in, if desired.

Other info:
The crab are not routinely handled.
Regular cleaning of the tat consists of removing old food and waste. Mold or mildew has never been an issue.
The only possible contributing issue I've seen was what appeared to be a few sand colored mites in the sub. I bathed the crab that were up but never saw any mites float off them and haven't seen any in the tank since. Mites have never been seen in my other tanks.
Deep cleanings consist of removal of any remaining exo, buried food, and things of that nature.

There you have it - everything I could think of offhand to help sole this mystery. Any input is appreciated and questions will be answered to the best of my ability. Thanks.

Randy

Sorry to hear of your trouble. I would say, yes you were a bit overcrowded. Es especially need a lot of space and deep substrate. Nothing else really jumps out at me. The mites you mention sound like harmless food mites to me. The other thing to mention is some crabbers have had a lot of bad luck with Es, even when housed in E only crabitats. Not to sound like I'm writing it off as something that "just happens". It's definitely cause to recheck conditions like you are doing and try to prevent in the future. The other thing I'm wondering is, how often are you deep cleaning?

Deep cleaning happens roughy every four months. I had read somewhere that E's need more space but given their small size (the biggest only being the size of a large gum ball), I figured 9 inches of sub wold be enough. Given the stories about how active E's are supposed to be, I'm really surprised mine spend so much time in the sub. When they are up, they're usually climbing to the highest point they can find. I know other people keep E's and PP's together, so I wouldn't think my methods are the problem because I've never lost any of my 10 PP's. I have to wonder if there is some sort of contagious illness in the tank that is killing them off.

I would hold out longer on deep cleans. Once a year or longer. This way your not disturbing them too often which may cause them to postpone molting or cause stress.

My Es are at biggest maybe big-mediums and I've given them about 12 inches of substrate. There's also only 4 in a 40 breeder with an exoterra topper and I don't think I'll be adding any more just so they have tons of space.

Sounds like reasonable advice on the deep cleans. Since I've never found a live one during a deep clean, I doubt that's an issue this particular time. Regardless of what happens with the remaining two, I'm done with E's. I've read a lot of good things about Indo's, so maybe I'll try a few of those next.

This is exactly what happened to me. I had started with around 12 Es in a 55 gallon tank with a foot of substrate. They started disappearing at the rate of about 1 per month, and in a year only the biggest three were left. I'm still convinced that one or a couple of those survivors ate the others. Sach was kind enough to adopt the remaining three (who by all accounts are mostly behaving for her) and I don't regret rehoming them in the least. They are a beautiful and fun and funny species to keep, and I really do miss the big guy so much.

I very much feel that with Es either you have a good group or you don't, and there's no way to know ahead of time if it's going to work out fine or not. I know there are several members on here who have kept Es without problems, but I also know there are just as many who experienced the same kind of issues you and I have. It does seem to come down to the personalities of the crabs themselves.

I did enjoy their antics when they were up and about but those times were usually around my bed time, so I didn't get to see it often. I'm inclined to agree with your belief about good and bad groups because I have also seen people with E's who are loads of entertainment.

Are you sure the ones who went down the first time did actually molt and not just go down to destress? The E's I lost were the ones who did not molt despite going down for 6 weeks, came up without molting and died. I lost two that way.

They all came from the same group at the same time though it sounds like, so it's hard to say because it could be something to do with them not being able to adjust.

I would say they were overcrowded, they need a lot of space not just to dig but above ground to run around. I find mine need way more space than my pp's. My E's weren't happy until moved into the 75g. But I don't know, if they were overcrowded i would have thought they'd stop once the numbers were down to only a few.

I don't know though, your conditions seem perfectly fine. was there any flooding that could explain multiple deaths? or misting with salt water building up too much salt in the sand? im not even sure if that would cause multiple deaths like that, as opposed to just burns.

This situation sounds so much like Wode's E's

I have 8 E's, and i had 10 but lost 2. Most of them i had for over a year, and the newest 2 were added in january. mine are 2 large, 1 small, rest are medium. I haven't had issues with mine except for the fact that it's very obvious my e's don't like my pp's, and my pp's don't like my E's, they don't fight, but yeah . Most of my E's are female though, of the 8, the 2 largest are females, the next largest is a male (who is the dominant crab in the tank), and then 3 more females, and i am unsure of the other two. My male is the most obnoxious crab I've ever met, and I don't know if it's because it's a male or what, but i could see there being issues if there were several of them who act like he does. I'm curious to know the genders of the ones you have remaining.

I'm positive they molted because all of them had tips missing from their legs and no setae. When they came back up, they had new black tips and lots of setae on their legs. There was no flooding and and while the initial mixing of the sub was done with salt water, misting has always been done with fresh water. The gender of the remaining two is unknown because they won't come out of their shells far enough for me to find out.

I also did mix with salt and misted fresh, and it realyl sounds like there was nothing wrong with your conditions.

I'd check out this thread, you probably have read it before but I'll link anyways in case you haven't.

viewtopic.php?f=29&t=94418

It talks about issues others have had, you definitely aren't alone. I don't think anyone really figured out why, just possibilities of some things that could help :/ but adding your experience to the thread could help some day with finding a common link, if there is any.

Thanks for that link. I haven't seen that thread before and found it very interesting and informative. If it's a 'kill or be killed' issue, it seems like there would have been attack on the surface at some point, but who knows. I never witnessed anything more than a kicking match between two crab that wouldn't get out of each other's way. It was pretty comical to watch and eventually one yielded and it was over. As frustrating as it is, not knowing what's going on drives me crazy and I may wind up getting a couple more just to see what happens.

Just from my personal experience with aggressive, murderous Es, I'm inclined to agree that it could possibly have something to do with them killing each other. Looking back, I think part of my problem was that I overcrowded the tank (I went by the crabs per tank guideline here, not exactly realizing that Es are a little different in their digging behavior and need more space than PPs) but it was also the same crab being aggressive each time. I guess there's not really any way to know for sure, we just have to take educated guesses. I'm so sorry for your losses though, trust me, I know how it feels :c If you do get more Es, I hope you have a better experience. I've decided not to chance it, even though Es are my favorite kindof crab.

I think E's just have strong personalities, coupled with loads of energy and extreme mobility. If there's one who is off his rockers, he might be a bully or murderer. Maybe he's got crab PTSD


Sent from my iPhone using Tapatalk

I don't think it's a matter of E's jsut being E's. Some people have had massive losses due to their E's, while others have been able to keep them fine, and several of those people have kept crabs a long time, the conditions were perfect, it doesn't add up why some have this problem and some don't, without there being some factor we are missing.

Might be the location they were harvested from, I looked up many places E's are native to, to try and see pictures of groups of them in natural habitat, and some of the places they came from are pretty nasty, i mean their natural habitat being destroyed, by humans, and just by nature and storms.

I saw several articles about how serotonin is found in many inverts, and studies have been done on other crab species and the affects of serotonin on them and aggression, and definitely many nutrients and foods can cause a serotonin imbalance in humans, not sure how easily it can be thrown off in a crab, also yes stress can do that in humans, as well as other factors, like vitamins and sometimes it just happens, if it works the same as crabs that would definitely explain it. If you read up on any studies about crabs and serotonin you will see the findings were inconclusive, with some showing increased aggression and unwillingness to retreat while injected with serotonin, and other inverts the opposite, showing less aggression when injected with serotonin, and increased aggression when injected with a serotonin receptor antagonist.

If you want to read one. It also talks about the aggressive stance in other crustaceans, which some of us have seen in our E's.
http://middarchive.middlebury.edu/cdm/r ... hip/id/339

Also I still feel like it's a gender thing. My female E's are calm, I don't see them climbing all over everyone, I don't see them get up in everyones personal space as much as my male does. Still active but they don't even act the same as my male. My husband calls the male "psycho", and I guessed the genders of 4 of them before i checked, with 3 being female and the one male. I think my smallest is a male too, because the baby acts obnoxious just like the confirmed male, just won't come out to let me look. My confirmed male is not aggressive towards the E's, but he does do this stance where he puffs up at my pp's, and he perches at the highest points in my tank, and in the most desirable spots in the tank, like on top of the moss pit, not in, just perches on top at the ledge where everyones gotta go by him. Another crab in my tank acting the way he does would cause a fight im almost positive.

My remaining crab simply stay buried during daylight hours. When they do come out, they will either run for cover or slam the door on their shells if they see any kind of movement. If these two don't survive, I'm not going to be heartbroken at this point. I'll gladly repurpose their 'tat for some Indo's or more PP's.