Mix all of the citrus slaw ingredients together in a bowl and set aside.
Heat a grill (or grill pan) on medium-high heat and grill the fish for 2-3 minutes on one side. Squeeze the lime over the fish and season with garlic, salt and pepper. Flip the fish and grill for another 2-3 minutes. The fish will likely break apart and that's okay.
Assemble the fish tacos by placing small pieces of fish in each taco, then top with the slaw. Garnish with avocado and lime slices.
