[header] How to cook fish on a barbecue [title] Clean the grill grate. [step] One of the trickiest parts of cooking fish on a barbecue is making sure it doesn't stick. If your grill grate still has bits of the last thing you cooked stuck to it, the fish's delicate skin and flesh will stick to the grate and the fish will fall apart. 
Clean your grill grate well with a stiff-wired grill brush. After you've scraped off all the bigger chunks of debris, finish the job by wiping off the dust with a dampened paper towel.