You need to take a piece of wood the length of the fish, place the wood on the scale and note the weight.
Then place the fish on the plank so it does not hang over and weigh them together.
Deduct the weight of the plank and you have the weight of your fish.
If it is your fish, pick it up by the gill plates and keep the head high.
If it is some one elses fish, pick it up by the tail and shake it a couple of times to rattle the stones out of its belly.
