HCA: Hermit Crab Association

This is going to be my second attempt at writing a post, since my first one was deleted when I clicked "submit."

I have a 65-70 gallon (different calculators give me different size results) that is currently housing 7 medium and 6 small PPs. I also have two 10 gallon ISOs up, one with 3 smalls and one with 13 crabs ranging from teeny-tiny to medium-large. Eventually the crabs from both ISOs will go into the big tank, which I am now beginning to think will be overcrowded. I'm trying to think of ways to expand my current set up to give everyone plenty of living space. What I cannot do is get a bigger aquarium. I cannot afford it (my current one came from a thrift store), I do not have room for it, and I do not want to move it into my second floor rental apartment because eventually it will have to be moved out. I also cannot set up a second tank because I do not have room for it. My ISOs are on the kitchen counter and the living room table, neither of which are good permanent places.

What I am thinking of doing is adding an Exo Terra extension like I've seen on this forum. I have found one on Craigslist for a decent price, but I want to find out more before I commit to buying it. I have a few questions.

1. How much livable space does the Exo Terra really add?

The one I am looking at is 18"x18"x24" and would add approximately 33 gallons of space. But how much of that is useful, livable, crab space? It would add space that I could use for second (and third!) levels and more climbers, but how about molting space? If the tank was taller I could make the substrate deeper, but there is no way to make it wider.

2. How sturdy is it?

I looked up the shipping weight of the Exo Terra and it is 50#. I am nervous about adding 50# of weight to the top of my glass aquarium, especially since it will be on one side of the tank and therefore unbalanced weight. Also, I know that you can work wonders with industrial strength velcro, but can it withstand cats jumping on top of it? Because that is going to happen.

3. How do you heat and light it?

Right now I am using a Reptile Combo Hood with a fluorescent UVB light and daylight and nighttime heat bulbs. I like overhead heat because it seems more natural to me and is easier to control. I really only like UTHs on small tanks, but if I add the Exo Terra I won't be able to use my hood anymore. What else could I use?

What do you think? Does anyone have some good Exo Terra-extension advice to give me? Or another solution?

What're the dimensions of your current tank? Id be glad to tell you the exact volume of it :3

The aquarium is 36 3/8"x18 3/8"x25."

According to this http://www.aquariumdimensions.com/ it is 65 gallons.

According to this http://www.firsttankguide.net/calculator.php it is 71.7.

Either way doesn't make much difference to me because I don't think 5 gallons or so will be the difference between me keeping 29 crabs happy or not. Just from looking at them in their tank I think it is going to be too small for everyone to live happily. It might be fine for now while the teenies are teenies, but that isn't going to last for long. i need to do something.

If you have the space, you could maybe combine both your ten gallons and your big tank by either cutting glass, adding large hamster tunnels, or placing the 10 gallons upside down on top og the big one and securing it with silicone... large crabs need roughly 4 gallons each so you really need 110 gallons of space for 29 crabs, so even if the big one is 71.7, adding 20 gallons would only make it 91.7. Medium crabs only need 3 gallons each, so 87 total, it would be tight. Possibly too tight. Personally I would combine them for now, wait until the crabs are bigger see what kind of living situation you're in at that point and then either buy a bigger tank or build a bigger tank if I've moved and have the room, or if not, consider placing some for adoption on this fourm. Many people here are looking for more and if they have the space to accommodate them it might be better for the crabs to do that. I don't know anything about the extender and how it works, but maybe if you connected it with pvc pipe or big hamster tubing or something like that, that could work sitting next to it with a glass lid, since that would be 30 gallons of space, if you connected both tens as well, that's an extra 50 gallons it really depends on what you can find room for. I don't know that flipping it on top will be good enough with that many crabs long term because of molting, but if you are creative enough,and have time and space, you can probably build something that will work for you with the extra 50 gallons. I'm going to spend the summer working on combing a 20 40 and two 10s, but I'm also low on space because I'm in college and my room at home is tiny and my campus only allows fish (I know stupid)

Personally I think adding a topper will not solve your overcrowding issue. Will it provide more climbing space and allow you to deepen the substrate? Sure. But that footprint of the tank remains the same and molting crabs typically dig down as far as they can go to molt - the extra depth helps prevent other crabs from running into molting crabs and to ensure molting caves are not easily collapsed.

For example, my 40 gallon breeder has an exo terra topper. When you put the dimensions into a calculator its around 95 gallons but the footprint is only that of a 40 gallon breeder (36"Lx18"W). I have 9 medium crabs in there and it's feeling quite maxed out to me. Especially when you take into account that they won't be medium forever.....I will need to upgrade or split up that crew eventually.

A lot of height is great for giving your crabs climbing space and deep substrate - but I think often the importance of molting space is overlooked. And I think too often we get caught up in gallons when calculating crabitat size and should take care not to forget about paying attention to that footprint. After a bad experience with overlooking a tank's footprint, I now try to make sure there's room for every crab if they were all to molt at once (which is not unheard of). There are differing opinions on space requirements....this is just mine.

That'd be a 65 gallon tank. Standard size :3

And I realize I missed a few questions.

2)I feel my exo terra is quite stable. I've leaned on it. The cats jump on it sometimes (they're not supposed to but....cats. Ya know?). I cut off the legs so it would sit flush to the top of the tank and it's secured with heavy duty Velcro. I then put electrical tape around the outside where the tanks meet to help keep in humidity. Mind you, my exo terra is the same length and width as the tank it sits on.

3) Right now I'm using a 35"x11" Ultratherm UTH insulated with one of those car windshield shade thingies, shiny side in. It's working well and temps range from upper 70s in the coolest areas to well up into the 80s (the surface of the glass where the mat is reads 111F at it's hottest spot). I also have a light strip for daytime lighting - right now with just an ordinary fluorescent tube but the plan is to use UVB. And a room humidifier piped in helps keep humidity high.

CallaLily wrote:Personally I think adding a topper will not solve your overcrowding issue. Will it provide more climbing space and allow you to deepen the substrate? Sure. But that footprint of the tank remains the same and molting crabs typically dig down as far as they can go to molt - the extra depth helps prevent other crabs from running into molting crabs and to ensure molting caves are not easily collapsed.

For example, my 40 gallon breeder has an exo terra topper. When you put the dimensions into a calculator its around 95 gallons but the footprint is only that of a 40 gallon breeder (36"Lx18"W). I have 9 medium crabs in there and it's feeling quite maxed out to me. Especially when you take into account that they won't be medium forever.....I will need to upgrade or split up that crew eventually.

A lot of height is great for giving your crabs climbing space and deep substrate - but I think often the importance of molting space is overlooked. And I think too often we get caught up in gallons when calculating crabitat size and should take care not to forget about paying attention to that footprint. After a bad experience with overlooking a tank's footprint, I now try to make sure there's room for every crab if they were all to molt at once (which is not unheard of). There are differing opinions on space requirements....this is just mine.

I happen to agree with you about the space requirements. I've had my 7 mediums for a while and I have an idea of what they like in regards to space, and quadrupling their number does not seem like a good idea. It was not intentional. First I only intended to buy a few more smalls and combined an online order with someone else who then backed out and I ended up taking all 10 (one died in ISO). Then I saw 8 crabs on Craigslist that were breaking my bleeding heart so I went and got them, figuring since it was only 8 tiny crabs I could figure something out...and it turned out there were 13 crabs, two of whom are mediums who will be close to large after they molt. And now I have 22 more crabs than I did two months ago and I'm scrambling for ideas on what to do to house them.

Do you think this crew will be able to live together for a time while I try to figure this out? Like a year? I guess I could keep the teeny guys in one of the 10 gallons, but I wouldn't like it. It's such a small space to work with, even with shower caddies added. There's barely space for decent water bowls, let alone climbing and running around space.