But is it okay to keep in the tank, it won't rot or anything since it's not aquatic?
So far yes. I've had it in there for about 2 months. A few leaves here and there have rotted, but once removed it's okay. If you have long vines I would just cut a vine off and "wrap" it to fit in the tank and roots should start growing. It takes a long time for them to start growing though. I really enjoy them as a floating plant and I think the fish do too
I don't know if this image will show because I've never posted an image on this site before. If it does than here's my new "tank". It's a critter keeper that only holds about 1.5 gallons filled to the point it is in the picture. I wanted a bigger one, but for some reason I don't know how to do math (I ordered it online and had to convert inches cubed to gallons. Apparently my conversion factor was off.) Anyway, it's bigger than the old one at least, so I can fit a little heater and a couple silk plants in there. I want to get him mug to hide in, but I don't know if there's really enough space...I really wanted a plant that laid more horizontal, but I had to order everything online, so I couldn't tell how the leaves stood. Oh well. He seems to like hanging out by the heater.