Step 15: Use the shape at the bottom as a guide to draw the anal fin the same way.
Step 16: Add the caudal fin on the right by using the curved line as a guide. Different varieties of bettas, like crowntails, may have fins that are shaped differently, so you can change yours if you'd like.
Step 17: Use the remaining shapes and lines as guides to draw the rest of the betta fish's body. Follow the path of the guides as you darken the lines to create the body. Remember that there are many varieties of bettas, so feel free to adjust the fins on your drawing however you'd like.
Step 18 (optional): For a cleaner look, erase as much as you can of the initial guide lines. Don't worry about erasing all of the guides. It's okay to leave some behind. Re-draw any final sketch lines that you may have accidentally erased.
Final Step (optional): Bettas are colorful, so instead of the usual shading, try coloring your drawing. Add some shading first using gray to give the betta fish drawing more dimension and volume. Pick the direction of the light source to draw the shadows consistently. Shadows are usually at the cool end of the spectrum, so use some blue or purple on the shadows. Add black to the betta fish's eye too. Pick the color that you want your betta to be and start adding a dark shade of that color to the shadows. If you want your betta to be red like this one, start with dark red or brown. Add the color lightly at first. Apply more pressure to your pencil to get a darker value as you cover the body. Add a few longer strokes at the base of the fins for the folds within the fins. Now use a slightly lighter shade of red to build up more color throughout the betta's body.
Add the color lightly at first and then darker as you cover most of the fish's body. Using different shades of a color, in this case red, gives the drawing more dimension. Continue adding the darker shade of red until you've covered most of the fish's body except for the tips of the fins. Now add another lighter shade of red on top of everything and push down a little harder as you go along. Adding different layers of color can be very time-consuming, so be patient and take breaks. You can also just add a single layer of red to the entire body for a simpler drawing. Add another lighter shade of red, like red-orange, on top of everything and push down a bit harder. Every time you add a lighter shade, push harder with your pencil to blend the previous colors together. Add some yellow to the body, especially the edges of the fins to highlight the tips.
If you have a pet betta fish, try to duplicate its color on your drawing. If you're making it a different color, remember to use various shades of it. If you use blue, for example, add some purple to the dark sections and blue-green to the lighter parts. For extra detail, you can add tiny curved lines along the body using a dark color for the scales. Don't forget to pause the "How to Draw a Betta Fish" video after each step to draw at your own pace.