fish & crayfish

Question
I have a crayfish and I would like to put some fish in his tank.  There is no lighting (crayfish need cool water: 40-70 degrees) and I know some fish need lighting. I need some fish that are big enough so they crayfish doesn't eat them, but small enough so the fish don't eat the crayfish.  Plus the tank is 30 gallons.  Which fish can go in the tank?   Sarah

Answer
To be honest, I am not sure there is a fish who does not need or benefit from lighting. All fish, as far as I know, need the day and night cycle to properly live. The crayfish, on the other hand, is not like fish and likes to be in caves and crannys, which is why he likes no light and cool water. The only thing I could think of is perhaps a crab or frog? But again, not sure as they may not be compatible with the crayfish. You could always get more crayfish. I am sorry I am not much more help, I have been brainstorming while I was writing this and researching but I cant find anything. Feel free to ask another expert as they may have more information I am not considering. Let me know if you need more assistance. I hope I have helped you somehow.