I have 2 newly acquired stingrays. They lived together before we got them, but I have noticed that they like to climb on top of one another. I believe the female does it more to the male than the male to the female. They are very young, and very small, and are definitely not at breeding age. Could this be a sign of dominance? Are they roughhousing like puppies would? Also, does anyone know what the least messy food to feed them is? We are swooping the net around the tank every day to get the little pieces of fish from floating in the water, and I am worried about the nitrite, nitrate, and ammonia levels if we leave them in there.