Adding a topper to your tank can not only give you more room to add deep substrate, but also more height for climbing objects and activities.
In the wild, Hermit Crabs will naturally spend hours climbing trees and other high up objects. They are excellent climbers and thoroughly enjoy climbing as a pass time.
They will also climb up high to sleep, this is a normal behaviour as they attempt to keep themselves away from predators on the ground.
What is a topper?
A tank topper is a second tank, placed on top of your current tank. Hence making it a "topper". Usually toppers will cover 1/3 - the full length of the base tank and will be similar in width to the base tank to avoid gaps.
What tank should I use as a topper?
You can use many different styles of tanks as your topper, from fish tanks through to reptile tanks. The one we highly recommend for toppers is the Reptile One or Exo Terra Reptile Tanks. These have front opening doors, making access to the topper much easier. You can often find these types of tanks for sale second hand on Facebook Marketplace or Gumtree at really good prices. You don't need to spend big bucks purchasing a brand new tank for your topper.
They do however, need slight alteration to make them safe. Usually these tanks will come with a mesh roof, and 1 small side panel that is mesh. You will want to remove the mesh lid and place your reptile tank upside down. The open lid becomes the bottom of your topper, for your crabs to climb through and the glass bottom of the reptile tank will now become the sealed roof. That just leaves the issue of the mesh panel. You can easily cover this by cutting a piece of Perspex to size and using Aquarium Sealant to stick it in place. This is a very important step, as any mesh gaps will cause your heat and humidity to leak out.
• Spare Tank (preferably a reptile tank)
• Aquarium Sealant/Silicone
• Tape Measure
• White Board Marker
• Perspex Cutter
• Extra Heat Sources (heat mats or heat cords)
• Lots of decor and hanging objects
• Hanging Plants
• Hanging Coconut
• Leaf Wall
• Tension Rod
• Hanging Hideouts
• Reptile Wall Backing
• Crab Swings
• Moss Pits
• Crab Nests
• Wood Pieces
• Coco Fibre
• Moss Pits
Getting your topper ready
Now you have your new topper tank, the fun begins! You can start to think out design ideas for what you would like to put inside your topper, and where you want things to go. The entire point of a topper is to add height for climbing, so ideally you would fill it up with climbing items.
If you are adding anything permanently like backing or hooks etc, it is best to add these to the tank before you place it on top of your main tank. We highly recommend using command hooks as they are sturdy, safe and removable. You can also stick items down permanently using Aquarium Silicone. This is crab safe and fast drying.
It's best to measure where your tank is going to sit and if you will have any open gaps. If the tank is too wide, you will have an overhanging gap at the front, if the tank is too small, you will have an open gap at the top of your main tank at the front. These are easy fixes by cutting Perspex to size and gluing it into those gaps. This prevents crabs escaping, and seals in heat and humidity.
Place your topper on top of your main tank and using a white board marker, mark out where the tank will be sitting. This is where you want to apply your sealant.
Once you have added your permanent features and everything has dried in place, it's time to move the topper to the tank and fix it in place.
It is vitally important that you stick your topper down and don't just rest it on top of your tank. If someone bumps the tank or you have other pets such as cats who like to jump on your tank, your topper can easily move and fall.
Firstly, squeeze out the Silicone Sealant onto the lines that you previously made on the main tank. Don't be shy in how much you use, this needs to work as a glue and a sealing device. Place your topper over the top of the Aquarium Sealant and gently push down. You can wear a glove and use your finger to slide along the edge of the topper to clean up the silicone and smooth it out. Make sure you have also Siliconed your extra perspex pieces in any gaps that you may have.
Give your topper a full 24 hours to dry before you start playing with it.
Decorating your topper
Only the part we have all been waiting for! Now you can decorate your topper. A hot tip is to add a leaf background to your walls and hang things. We often get asked how do crabs access the topper? If you have a Leaf background in the main tank that joins up to the topper leaf background, they will often use this to climb into the topper. But you can ultimately add any climbing items that you would like, these include ladders, large pieces of drift wood, ramps etc. If there is a way into the topper, your crabbies will find it! Ultimately, your design ideas for your topper are endless!
Cons of having a Topper
Having a topper is a great way to add extra height and climbing space to your tank, but it does come with some cons.
You now have another tank to heat and keep humidity in. The topper will suck the heat and humidity out of your tank and into the topper, if it is Winter or you live in a low humidity area, this may become a problem as your humidity and heat drop.
You can add heat sources to your topper, but bare in mind that heat rises.
We also hear of people thinking that if they add a topper to their tank (creating more space) that they can now add more Hermit Crabs to their tank. That's simply not true. Hermit Crabs need 38L of space each. We aren't talking about airspace, we are talking about moulting space. Overcrowding on top of the sub is not as dangerous as overcrowding beneath the substrate. Each crab needs to be able to dig down deep and have a safe area where there is little chance they will be found by a tank mate during a moult. If you are adding a topper for more Hermit Crabs, I'm afraid toppers are not for you. It may be best to invest in a longer, larger tank.
Another thing to remember is that toppers are luxuries, not nessessaties. Make sure your main tank is upto scratch first before worrying about adding a topper. It is not something they need, it's simply a want.
During Winter, with low humidity and already low temperatures, we close our topper off so that our crabs cannot access it. This helps the warm air and humidity stay inside the main tank. I cut a square piece of Perspex and place it inside the topper, sitting snuggly on the shelf just above the main tank.
Come Summer, we will usually open the topper back up again for them to explore.
Enticing crabs into the topper
Your crabs will find the topper on their own, but if you are keen to speed up that journey, try adding something exciting into the topper like some Popcorn or a piece of Shrimp. Those treats usually get crabs moving faster.
As long as there is access to the topper, they will find their way.
If you are looking for ideas and inspiration for your topper, we highly recommend joining the Facebook group "Crabitat Dream Builders" link below.
• An empty Reptile One tank ready to be made into a topper.
• Permenant items added into the topper, and a piece of Perspex glued to the bottom front of the tank to cover the gap.
• Tank has been attached to the main tank.
• Topper tank glued to a main structural part of the tank lid, making a little shelf inside the topper. Grass has been added to the glass.
• Finished topper ready for exploring. I usually alter the decor items within the topper every summer to keep it interesting. The above design is our 2023 summer topper.
Below are hermit crab owners toppers from around the world!
• Tank belongs to Lynnee Wasson.
• Tank belongs to Holly Long Suddeth.
• Tank belongs to Jeanne Brady Schreib.
• Tank belongs to Aliesha Perry.