Substrate method update – moss

Photo Credit: Mary Milhorn Trichoderma outbreak in spaghnum moss

Photo Credit: Mary Milhorn
Spaghnum moss layered under sand

We are amending our recommendation regarding moss. While moss is safe and should be offered in your crabitat we no longer believe it is safe to MIX the moss into your substrate or to layer it under your substrate.

In the video below you will see a newly set up crabitat (not the owners first crabitat, she was upgrading) with moss layered under the substrate to test a natural false bottom, as was previously done on All Things Crabby. It rapidly developed an out break of Trichoderma that went all the way through the moss to the other side of the tank in one week.

After some discussion it seems there is no way to prevent this when mixing the moss into the substrate. So while it may not happen every time (I had a vertical tank set up the same way with a moss layer and did not have this issue), if it does happen it would be disastrous and require a full tear down of your crabitat. There is no detriment to your set up if you keep the moss on top of the substrate. This does not mean you should be worried if your hermit crabs churn a little moss into the top layers of your substrate.

So as of now our official stance on moss is that is should be on top of the substrate only and not purposefully mixed INTO the substrate.

Tips when purchasing moss:

  • Inspect the package for water damage, smell the moss itself. It should smell earthy but not like mold or mildew.
  • Moss is not considered perishable so a retail store that does a high volume in sales may have fresher moss.
  • How humid is the area where the moss is sold?