| | Re: immobilizing zebrafish
Pin them in low-melt agarose, then transfer them to the dish, perhaps? Pour a dish of low-melt agarose, then drop the fish onto the dish and drop more agarose on top of them, aligning them as necessary with a fine tweezer tip as it solidifies. Pin them, then cut away the agarose and remove the fish.
I used to do experiments that required immobilization in agarose, and if I sent them improperly sometimes i would free and re-set them. You have to be careful, though - it's easy to injure the fish when removing them from the agarose.