First time requesting feedback, joining in any competetion, and taking a sketch to finished stage. Tried to use the kim jung hi method of using simplest representative forms and let details convey idea

Am i getting the " Likeness " of mermaids correct ? And is the design and composition good ? Looks accurate to me but i have had moments when i drew a demon and my sister asked "Is that a whale or dolphin ?". Wishes to take this to a finalised stage with colours, so suggestions about that would also be much appreciated.