Ice 2-layer cake smooth in light blue buttercream; place on foil-wrapped board. Randomly spray sides and top for water effect. Attach Flounder decorations to cake sides, about 1 1/2 in. apart; pipe tip 14 outline coral. Pipe tip 6 irregular zigzag bottom border; position shell and starfish decorations on sides and top. Position candle. Print message with tip 3 dots.