Yeah, they almost gave me a heart attack, I was working late at the office and heard this creaking noise, thought the floor was giving way.....was them getting all macho with each other - so funny. They have this little place in the middle of the tank, just about some rocks and framed by the plants, they use it like a town square or something. They start feeling full of themselves, they swim into the middle and it's like "Yeah, come on, who's gonna take me, come on, dare ya!" someone will square up and they'll get all flare-y, then a minute later another one will be in the same place, doing the same thing, like...."c'mon, I'm tough, ya bunch of sissies...."