A step-by-step tutorial with pictures.
1. Mark the middle lines: fold the square sheet of paper both ways.
2. Fold the left and right sides to the center.
3. Mark the lines: fold the top and bottom parts to the center.
4. Unfold the lower corners sideward.
5. Turn your origami over and fold the corners to the center.
6. Turn it over.
7. Draw eyes and gills.
A Step-By-Step Tutorial
1. Fold the square sheet of paper diagonal-wise.
2. Fold one lower corner upward on the crease.
3. Fold the lower corner frontwards on the crease.
4. Fold the corner to the line down.
5. Fold the left corner frontwards on the crease.
6. Fold the corner downwards.
7. Fold the right corner backwards.
8. Turn it over.
9. Draw eyes and gills.
The fish is ready!