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Question on number of crabs

Posted: Wed Feb 11, 2015 4:25 pm
by thermidor
New to the forum and appreciate the "helpful" versus "critical" orientation you seem to have. I too had crabs in high school and decided to do so again many years later.

So much conflicting info out there. Some places will tell me I have way too many crabs but to me it seems pretty much "just right".

Here is the situation until I have a chance to do pics. I have a 40 gallon that has 9" sub (EE/ play sand) in front and then some acrylic barrier (sort of like a step-up level or terraced) so that it goes up to about 13" deep in the back. The reason the sub is lower in the front is because it is an ExoTerra tank which I guess is sort of controversial; but I LOVE it because it is so easy to clean and maintain. I personally think the crabs can figure out what the sand level is if they want to go deeper but would appreciate feedback. I have 2 coconut hides, one cork round hide, and a tree root with holes in it for hiding inside and behind. Large grapevine limb that goes to the top for climbing, net on entire rear of tank. Very large fresh and saltwater pools with bubblers; a 5 x 7 second story shell shop that is packed. Humidity at 85-88 (concern this might be a tad high?) and temp at 82-85. Massive variety of food; proteins, calcium, worm castings, cuttlebone, etc. (multiple dishes for sharing) The tank has been up and stable for 6 months.

I have 8 E's small-medium to small, and 3 medium PP's. Recent additions were 2 large strawberries. So that's 13 crabs in a 40. HOWEVER>>at least half of the E's are always under; one of the strawberries is now.

I have never seen any aggression; many E's and at least one PP have successfully molted. The e's climb, run around and dig, the PP's only come out when they think no one is looking and the strawberry who is up now lets me rearrange things around him and is totally confident.

Also I was told that the light should be on all the time; that just seems wrong to me but I am doing it. I would assume the crabs need a dark period, but on the other hand it is nice to be able to go and see what is up at any time. If I go back to doing a dark period will the crabs stop coming out during the hours when I can see them?

Sorry so much info, appreciate comments.

Re: Question on number of crabs

Posted: Wed Feb 11, 2015 4:33 pm
by CallaLily

It is important to provide a normal day/night cycle for these guys. Your conditions sound great otherwise. I'm glad to hear you've had good luck with your Es. You'll find varying opinions on the number of crabs per tank size. There's a thread with guidelines in this section, along with a lot of other helpful info about crabbing. I look forward to future posts and pics. :D

Re: Question on number of crabs

Posted: Wed Feb 11, 2015 10:45 pm
by wodesorel
Constant light throws off their molting cycles which can eventually kill them, so definitely get them on a day/night cycle. How are you heating? Did the light need to stay on because it's providing heat? The temp can drop a little in temp at night, but using a night reptile bulb in red or black will allow you leave the heat on 24 hours a day and keep the temps up for the Es.

My only worry will be the Es as they grow. It's great that you haven't run into trouble and I hope to heck that you got a good batch of Es! Generally though as they molt and grow larger they'll get more testy with their tank mates. Just watch them closely and make sure your numbers aren't starting to dwindle. The problem with crowding crabs is when they do molt, as it's easier for troublemakers to stumble across a helpless crab. As they grow larger and need more space to molt, it becomes an even bigger risk. Seeing surface aggression is fairly rare, it's the noticing that there's less crabs over time that is the real problem.

Most people here who use Exo-terra tanks use the plexi barrier at the very front which allows them to fill the entire tank with as much substrate as they need. :) They can very nice when access to the tank becomes a problem. Going up and over is not the easier thing to do on a daily basis!

Re: Question on number of crabs

Posted: Thu Feb 12, 2015 12:23 pm
by thermidor
Nope the light thing was recommended to me by someone on another board. It's just a compact fluorescent so I don't think it contributes to the heat much; the lowest temp my house ever gets is 76 (hubby won't tolerate any lower) and during the day the AC is set to 78 (living in CA it is hot ALL the time and we run the AC all winter long! Have not turned on the heat once in 5 years!) If worse came to worse and it dropped to 78 at night that is ok, right? I freak out if it gets under 80 degrees. Again, I read varying opinions that claim that the strawberries need it to be 85 degrees all the time. But surely even on tropical beaches it stays balmy at night but I am thinking 78-80 degrees?

I have a large UTH on each end of the tank for heat.

My lil'est E just popped up from his molt this morning so I think all are accounted for :) If I start to see problems I could do a second tank for the little buggers but I am hoping for harmony.

I don't want anyone to get hungry for calcium (i.e. looking for tasty exos underground) so I put in tons of eggshell among other things and they devour that.