Add Box2D Collision to Game

I have created a simple game using cocos v2 with Box2D integrated into it in XCode. I already have the physics and body set up for my player sprite that I want as well as the world and the boundaries using Box2D so all I need is the collision for the enemy fish and the sand. My game is 100% done besides the collisions so all I need is someone to create accurate collision detection in my game. DO NOT EDIT ANY OTHER CODE THAN COLLISION. I already have a simple collision detection method set up which I will not be using once the Box2D collision is integrated. The collision must be accurate and work with the game I already have created. It must not change or alter the physics or gameplay I already have created. This should be a very simple project for someone knowledgeable in Cocos2d with Box2D. I will go into further detail via PM. *** I provided a screenshot to get a better understanding of what the gameplay looks like ***