Hey, I was going through a few videos and saw one on African butterfly fishes. I did some research and saw that they should be kept in a 29 gallon, and I have a 20 Long. Since they are surface dwelling fish, is it ok if I keep one in my 20 long? (20 long and 29 gallons have the same amount of surface area). Also, do you think its possible to keep a few dwarf crayfish on the bottom with the butterfly? Thx.