Consider the type of fish you'd like to paint and its features. Flounder have both eyes on one side of their heads. Most fish have a wide set of eyes on the sides of their heads; and some have eyes at the sides, but placed fairly close together. Some fish have long, thin snouts and others stubby snouts. Sharks have two sets of pointy teeth, but other fish have tiny, harmless teeth.
Choose where on the pumpkin you want your fish's face to be. You are not limited to keeping the pumpkin upright. If you have trouble, turn the pumpkin all around and ask yourself which way it is shaped most like the fish of your imagination.
Place the eyes first as these are the most outstanding facial feature of almost any animal. Draw them on your pumpkin with a fine marker so you can edit their size and placement with little or no difficulty. When you have sketched eyes that please you, go over them with a darker, thicker marker.
Draw the fish's mouth on your pumpkin with a fine-tipped marker. Keep in mind that because of the facial structure, fish mouths tend to look drawn and pouty. Keep with a traditional fish face, or make a mouth that suits you. When finished, outline it in thicker marker.
Draw a nostriled nose of your choosing in the center of your pumpkin fish's face. When you are satisfied with it, darken the nose up with bolder lines.
Paint your fish's eyeballs, mouth and nose with folk paint. Remember to detail each eye with an iris and pupil.
Choose the colors of your fish and begin painting backwards from the face. Make scattered scalloped patterns to give the illusion of scales. After the paint dries, spray your project with a clear gloss to make it shiny.
When the paint and gloss are completely dry, make and attach foam or construction paper fins and a tail with hot glue. Use the same colors you used for your fish's body. There should be fins on each side of your pumpkin fish and one on the top. Any of these attachments can be the design of your choosing, but keep in mind a triangle shape is closest to the real thing.