A "Little" Mermaid (Patreon)

"Did you lose, this?"

Why are mermaids always depicted as small and dainty? I like to imagine that a mermaid, technically a fish, would continue to grow the longer they're alive. If they're mostly unopposed in the waters, wouldn't they just keep eating and continue to grow? Wouldn't they grow to be over a mile long like our mystical friend here?   

There's less hours in a day than I think there are.. That, and I kept going, "but what if I added another layer?"