plants keep getting dug up

I had some plants in my ten gallon that I just took down and I added them to my 155 but someone keeps digging them up each night. I'm pretty sure of the culprit a Cactus Pleco that has been in the tank for almost a year and I know I've seen it digging in the substrate at night which is the only time it comes out. But I guess my question is how do I keep my plants planted in the substrate it's just plain gravel because that's how that tank has been set up since day one two years ago and it's a very small layer of gravel because I underestimated how much was needed for the tank. Also the tank has an undergravel filter I hate the thing but the person who had the tank before me glued it or something to the tank because I could never get it out. So is there anything I can do for my plants? I've thought about get some pots and planting them but I know there's not enough gravel to plant them in the gravel so they would have to be visible and I know the other person in on all this wouldn't like that so is there something else I can do to keep my plants planted?

 

Have you considered switching to plants that do not need to be planted, but grow just fine free floating?

 

You might also get a few small decorations or rocks and tie the plants on with sewing thread and then cover the roots lightly. I have to tie some of my plants to the decorations (my anubis) and eventually the roots have grown on to the decoration.

 

I do have java moss, java fern, anubis, and hornwort... plus the plants that keep getting dug up I can't remember what they are anymore I've had them for over a year now I know they are a kind of Crypt but I can't remeber which kind they are. will they do ok floating for a little while until I can do something for them?

 

I have the same issue with my blood parrots. True, I've been impressed by the fact that they've been getting their aquascaping degree taking that on-line course, but, it doesn't mean I like all the rearranging they do.

I have to replant, then take small stones and place them around the base of the plant. They may bite a leaf or two off, but it seems to do the trick.