i was told they are totally loving to stay in water, this pet shop advice so i got a book and read they need to come above surface at times with the help on bogwood or tall decoration. i was going to have a try here in my 16g which has swordtails, guppies and a few apple snails. i think fish be ok has surface high swimmers yea but snails i could move to other tank incase they get ko'd by crab.