Once upon a time when I was a new hermit crab owner, I did everything wrong. I used the overpriced metal cages you buy on the boardwalk that usually comes with a free hermit crab.
If I never changed my ways and bought the right kind of enclosure, my pets would most likely not be alive today.
The best enclosure by far is a glass aquarium tank. The glass exterior maintains a humid, tropical environment that hermit crabs love. I use the Aqueon 10 Gallon Black Aquarium, available on Amazon.com. Not only is it fairly priced, but it also comes in the mail well packaged in record time. This tank is my top pick for anyone starting out with their hermit crabs.
I like how the tank is simple and well made. This gives me the freedom to decorate the interior however I want, without having to worry about leakage or cracks.
The aquarium measures 20.25″ (length) by 10.5″ (width) by 12.5″ (height). This is the perfect size to sit atop a bookshelf or countertop. You can buy an aquarium stand for simplicity and aesthetic appeal, but more on that later.
The reason why I use an aquarium instead of a terrarium is the thick glass. It’s able to withstand the weight that comes from the crab’s substrate, decorations, etc. With an aquarium, especially such a high-quality one, your hermit crabs will be in a safe and secure environment.
Try a 20 Gallon Tank
10 Gallon aquariums, in my opinion, are perfect for new hermit crab owners. They’re the right size to get a feel for your hermit crabs. Just keep in mind that your hermit crabs will outgrow their tank in a year or two.
If you have a large number of hermit crabs, avoid the stress of moving your crabs to a larger home in the future and go for a 20-gallon aquarium.
The best quality tank I can find on Amazon is the Aquarium Masters 20 Gallon Long Aquarium. It’s perfect for hermit crabs with its very wide and expansive interior, which is something to look for when buying aquariums.
Quick Tip: You don’t necessarily want a tank that’s taller. Hermit crabs do better with aquariums that are “long” or “breeder”. With a large and wider base, your hermit crabs have more room to crawl, burrow, and hide.
The only issue I have with this product is the price. The outrageous price tag is due to mainly the cost of shipping such a heavy, fragile item. Aquariums, however, sell for much less at pet stores. If you are able to, I highly recommend buying larger aquariums at your nearest pet store.
Make Sure It’s The Right Size!
Before you buy your aquarium, it’s important to make sure your little crustaceans won’t be cramped. It’s easy to underestimate how much space a food bowl, two water bowls, shells, and decor takes up.
Lucky for us, some experts over at hermitcrabassociation.com came up some guidelines on how many hermit crabs fit in a tank per gallon. Click here to check out JMT’s crab per tank guidelines.
Quick Tip: Most hermit crabs sold at stores are small or medium sized, just smaller than a golf ball. A 10-gallon aquiarium will easily house about 3 or 4 crabs of this size.
First things first, measure your hermit crabs. For simplicity, measure the size of the shell instead of the crab. The process is simple. If your crab and its shell are slightly larger than a golf ball, it’s large.
- Teeny = marble
- Small = quarter-50c piece
- Medium = 50c piece-golf ball
- Large = golf ball-tennis ball
- Jumbo = baseball
I made a table depicting JMT’s crab sizes per gallon tank. Each number is the maximum amount of a certain size that can fit in a tank. For example, with a 10-gallon tank, you can house 8 teenies, OR 6 smalls, OR 4 mediums and so on.
| Tank Size | Teeny | Small | Medium | Large | Jumbo |
| 5 Gallon | 4 | x | x | x | x |
| 10 Gallon | 8 | 6 | 4 | 2 | x |
| 20 Gallon | 12 | 9 | 6 | 3 | x |
| 30 Gallon | 16 | 12 | 8 | 4 | x |
| 40 Gallon | 20 | 15 | 10 | 5 | x |
| 55 Gallon | 24 | 18 | 12 | 6 | 2 |
| 75 Gallon | 32 | 24 | 16 | 8 | 3 |
| 92 Gallon | 40 | 30 | 20 | 10 | 4 |
It’s important that you keep more than one crab in your tank in case they get lonely. A 40-gallon tank could house a single Jumbo, but he or she will not live very long due to loneliness.
You can extrapolate combinations of different-sized hermit crabs from this chart. The general rule of thumb is if you only have 1/2 the listed number of a certain size, then you also have room for 1/2 the listed number of the size prior.
For example, let’s say you have a 10-gallon tank. You have room for 1 large and 2 mediums, 2 mediums, and 3 smalls, or just 4 mediums.
Need a real-life demonstration? Let’s take my two crabs: Dazzle and Clarke for example. Sadly they’re both molting, but I have Clarke’s old shell.
Clarke is rather young. I got him from the pet store when he was a borderline “medium”. His shell was a tad larger the size of a 50c piece or diameter of 1.25 inches.
Dazzle is slightly larger, which means I have 2 mediums in my 10-gallon tank. According to JMT’s chart, I am in the green when it comes to tank size. If I wanted to I could fit 2 more mediums, 3 smalls, or 6 additional teenies.
Summary:
- If you’re a new owner with 2 to 4 medium-sized hermit crabs, go with the Aqueon 10 Gallon Black Aquarium.
- If you want a tank you won’t need to replace in a couple of years shipped right to your door, buy an Aquarium Masters 20 Gallon Long Aquarium.
- Before buying either, be sure to measure the size of your crabs or keep a certain size in mind when buying your pets. This will make sure your crabs aren’t cramped in their new home.