I've owned some tile fish in the past and actually have three flashing tiles coming in tomorrow (fingers crossed). I love Tile fish, the purples that I have owned in the past became extremely docile, actually letting me hold them.
In my experience, once you get them eating, they are pretty much bullet proof. I lost both my tiles to jumping. Check and then double check to make sure there is not a space they can escape from because they will try to jump without question.
Beautiful fish, good luck with them.