import com.greensock.*;
import flash.events.MouseEvent;
import flash.events.Event;

fish.addEventListener(MouseEvent.MOUSE_DOWN, onDown);

function onDown(e:MouseEvent):void{
addEventListener(Event.ENTER_FRAME, update);
stage.addEventListener(MouseEvent.MOUSE_UP, onUp);
}

function update(e:Event):void {
TweenMax.to(fish, 2 ,{x :mouseX, y: mouseY});
}

function onUp(e:MouseEvent):void {
removeEventListener(Event.ENTER_FRAME, update);
stage.removeEventListener(MouseEvent.MOUSE_UP, onUp);
}