I have sand as a substrate in my Bichir tank. They will bury themselves in the sand from time to time but I am looking for something I could put with them to stir the sand up more. Not a lot but to get rid of the air pockets that form. Now I stir the sand up once a month when I do a large water change. Is there a fish that could help? Maybe a crayfish? or would they attack my bichir.