Watery worlds -- Inside a fish -- Fish through the ages -- Fins, tails, and swimming -- Gills and breathing -- Skin, scales, and colour -- Fishy senses -- How fish breed -- The shark group -- "Snakes of the sea" -- Catfish, cod, and anglerfish -- Flattened fish -- Fish of lakes and rivers -- Seashore fish -- The colourful reef -- Open ocean dwellers -- Fishes of the deep -- Fish in trouble -- Animal classification -- Animal phyla.