A little while back a hydra population became established in one of my newt tanks. The tank is heavily planted, and there are a variety of crustaceans/microorganisms, with regular boom and busts of moina. Seeing this as indicitive of a balanced ecosystem, and having read of their harmlessness toward newts, I assumed they would make a positive addition to the aquarium community. The events that followed my first observations made me think otherwise. The newts became very hydrophobic, and now only go into the water briefly, leaving it frantically as if it all suddenly turned into battery acid. Furthermore, I've even seen the newts brush up against hydra on the glass, where they jerk their body away in response to the stinging cells. Should I make enemies out of these evil cnidarian invaders, or is something else behind all of this?