Step 10: Add a couple of curved lines under the eye for the gills.
Step 11: Use the lines on the lower right side as guides to draw the neon tetra's pectoral and pelvic fins. Follow the basic path of the guides as you darken the lines but make the shapes curvier for a more organic look.
Step 12: Use the other two angled lines on the left side as guides to draw the dorsal and anal fins. Again, follow the basic path of the guides but make the lines curve more as you darken them. The anal fin should be wavy to represent motion.
Step 13: Now draw the caudal fin using the triangle-like shape on the left as a guide. Darken the top and bottom lines. The line for the end of the fin should come in more toward the body.
Step 14: Use the remaining lines and shapes to form the rest of the neon tetra's body. Simply darken the lines as you follow the path of the guides to create the outer shape of the body.