Upset Isopods

[IsabeauBleue]

I've been messing around in my bug tank, which holds "native" isopods, millipedes, African night crawlers, and one very happy earwig. I've added 8 inches of potting soil and put my root bound peace lily in this 20 gallon long tank. I've also added a thin layer of Indian almond leaves that I had left over from redoing my fish tank. I did this all last night. I removed the bark pieces that originally filled the tank, collected from a tree that was cut down in my yard before we moved in.

Now, I have hundreds of isopods who are walking along the glass over and over. There are still at least a hundred buried in the substrate, making tunnels with the worms and millipedes. But I've never had it were groups of these guys are walking the perimeter. Any ideas why? I'd had a small amount of potting soil in the cage before, covering half of the cage. They didn't seem to mind it. It's 95% peat moss and 5% perlite.

Any ideas on how to get my isopods to settle down again?

 

[Jacob Ma]

You can increase the aeration of the tank like by having many holes on the lid of your tank (mesh works fine too). Though in doing this, you risk lowering the populations of your other species too, but ventilation is the simplest way to prevent your isopod population from growing out. Could you post a picture of your setup perchance?

 

[IsabeauBleue]

Aeration isn't the problem. I don't keep a lid on the tank at all because the plant is too tall. I'm also not worried about my population count. I'm worried that the isopods are upset about the huge changes I made in the cage. But, either way, here's a few pictures of my tank.

 

[Jacob Ma]

From the pictures, it looks like the isopods are looking for a place to both hide under and have a steady supply of food. It seems the placement of those leaves has created an inverse effect on the surface level of humidity, as the very top layer is looking a little bit drier than the rest of the soil. This behavior is common in isopods when the humidity is lacking, so their food cannot grow as well and they cannot keep themselves moist, which I notice in some of my drier potted plants. I would try crushing up a nice portion of the leaves in the enclosure and submerge some of those leaves. Yes, the leaves are dried and seemingly suited for isopods, but the leaves need to undergo a certain amount of decomposition before there is enough algae and fungi for the isopods. A slice of potato, apple, or orange peels can be thrown in modestly so you can invite a healthy amount of these fungi to the leaves, while the animals can have a snack in waiting for the fungi to replenish, but be sure that you remove the food in about a day or two to prevent this from growing out of control.

The worms may also play a part in the isopods' behavior, as when they further break down the soil, the soil gets much finer and compacts more easily. So while this may benefit the plant, the animals cannot burrow as easily when the soil expands and contracts from the water being added and removed. This is why balance is important in a soil ecosystem such as this, because the worm population is kept in check by a number of different other animals, especially of an invasive worm species like the nighcrawlers. You can try to mitigate this by replacing 25% of the soil every two weeks to a month, depending on how severe the situation is, or removing a few worms to feed to another animal such as an amphibian as long as you know the soil was not treated with any pesticides.