I have made them for fairs. Because of the shape of the bag, there is way more soap in themthen people think. Mine are generally about 5 or 5 1/2oz & I can sell them fairly well for $4.00 a bag.
The trick is to put a straight pin through the bag & into the fishes mouth to hold him in place untill the soap hardenes around him or he will flaot belly up. You also want to mist him well w/ alcohol so you don't get an air bubble around him when you pour & the soap fully attaches to the fish.