In fact, everyone is half right. The iron sheet is attached to the bottom of the fish's stomach and guided by a magnet, so that the fish will not suffer losses and will naturally follow the magnet. There are multiple magnets below, which can be controlled separately. This has just been denied by Teacher Fu. There is no fish abuse, and there is no magnet in the fish. But I think it is feasible to stick the iron sheet under the fish's stomach. After the performance, the fish will still be alive and well. The other one, which frame? There are fish in the fish tank with transparent plastic clips and then hidden in the interlayer of the fish tank. When the magician holds the finished painting (specially made according to the photo of the fish) in front of the fish tank, once the painting is removed and moved, the interlayer of the fish tank disappears. Now the caught live fish in the fish tank is released, and the fish swims forward, and the performance is successful, so this prop can be carefully made.