DIY Mermaid/Fish Scale Nails! Start with a base coat of one of the colors your using for the dots. Choose 4 to 6 colors. Starting at the tip of the nail make a line of dots using a different color for each dot. You can use the nailpolish brush or a dotting tool. If using a dotting tool remember to wipe it after each color. After the first row just keep making rows, overlapping like the scales of a fish. Let dry completely so colors don't run. Top Coat to seal. Yay!