ok so today i went to the lfs and i got some juvenille "PACU" supposedly, i put them in my tank, and they started to tare apart the goldfish i had in there, upon further investigation, i caught the little guys and examed them, they have teeth and are very fast with there jaws, the teeth are like little needles. i will post up some pics, but my question is there any way to tell when they are this small.