I considered making a mermaid bento for a long time. Today I finally have one to share. I made her out of Cheddar cheese. She is a bit strange looking but I like her. I am sharing templates in-case you want to cut your own similar mermaid out of cheese. But for a better looking mermaid please see this link.
Left Side: Quinoa with black beans, (I used more bell pepper than the recipe called for), I cut the mermaid pieces from white and yellow Cheddar and used small dots of cream cheese to hold on her head and shells. I dipped toothpicks in gel food coloring for her face and belly button.
Top Right: Green and red grapes
Bottom Right: Plain Greek yogurt with blue sprinkles