Clean the fish and remove slime from around the scales with salt and vinegar. Since fish scales can be very sharp, wear latex gloves whenever you are handling the fish to keep from getting cut.
Place the fish on top of plasticine clay to provide a better painting surface and help keep the mouth of the fish open. Fan out the fin and tails, then use straight pins to help keep the mouth open. Push the pins through the mouth and into the clay beneath to secure.
Use a soft bristle paintbrush to apply the ink (or acrylic paint) to the fish. Gently move the brush in all directions over the entire fish, making sure to cover the eyes and lips.
Place the rice paper over the fish with one hand and press firmly. Make sure to cover all parts of the fish, and be careful not to move the paper around once it has settled onto the fish.
Remove the rice paper from the fish. Peel the paper back, starting on one side of the fish, and slowly continuing to the other side. You have now completed your first fish print.