I have 2 dwarf Gouarmis. One neon orange and one neon blue. The tail on the orange one is much better looking than the tail on the blue one which is a bit on the short side and does not look fully developed. I have noticed that sometimes the orange one seems to dart towards the blue one when he is not looking and I am certain he is taking a swipe at him. Other times they will swim around together but I am guessing the orange one is nipping him which explains why his tail does not look as developed. Is it normal for one of them to do this to the other? Not sure how you tell if they are male or female.