Razor fish live in a burrow in the sand which can be up to 3 foot deep in depth,a common way of collecting them is to walk backwards over the sand,and as you get near a Razorfish hole,you will see a spout of water shoot out of the burrow,locate the key shaped hole and with a plastic bottle "washing up liquid bottle will do" filled with salty water.Then squirting some down the key shaped hole this will make the Razorfish clean its burrow in dislike to the concentration of salt,and it is at that point you can carefully pull the Razorfish out,being careful not to pull it away from the shell.