The body covering of the fish is quite different from that of mammals, it is made up of living cells as far as the outermost layer. There is a coating of slime over-all, which forms a wall against disease and parasite attack, reduces friction, an aids in making the fish water tight, for without it liquids would move through the body wall uncontrollably and disease would attack the fish and lead to its sure death. So if you have to handle a fish, wet your hands first and try not to get in touch with the gills, slide off the slime or put pressure on the main body of the fish. Gently grab the tail and cup the belly to get a quick photo and return the catch to the water. Be sure to release the fish when you feel it is strong enough to let go and swim safely away. No matter how careful we are we will all kill a percentage of the fish we catch and release. So try not to keep the fish out of its environment too long. Sometimes I hold my breath when I take a fish from the water and do not breath until I return it to the water. So you must be gentle but swift. Also try to use barbless hooks to make removing the hook from the fish a quick and easy task.