Thought these were springtails at first, but they move much faster and look like they have slightly darker abdomens and longer antennae. They are about the same size as adult springtails, maybe a bit larger. I saw one flying gnat in my tank recently, presumably a fungus gnat. But these insects don't fly when I disturb them - any ideas on what they could be? Or are these actually springtails and I'm just going crazy?

In my garter snake tank with isopods and springtails. I thought these might be springtails but they don’t move erratically enough for me to feel confident in that guess. They’re also only found around my substrate/hardscape, and not on the snakes. I think everything’s ok, but this is my first bioactive tank and I’ve had it for about a month, so I’m still very new and would appreciate reassurance or tips to improve conditions!