This battery-powered fish in a glass bowl is, once set up, quite a realistic-looking little thing. The fish is attached to a power pack section under the jar lid by a fine filament that's almost invisible when the bowl is filled with water and, when in motion, 'swims' in random patterns around the middle of the fishbowl. The thin plastic fins and tail really do look as though the fish is moving them.
The fish can be switched on for a specific period of time, or set to respond to a tap on the top of the jar lid. When the fish is in motion, it's accompanied by a colour-changing light show. Fish, jar, batteries and a little bit of scenery (in the form of fake pebbles - totally unrealistic - and seaweed) are all included, so all that's needed is some water.
My nephew loves it, but it's definitely the grown-ups who've played with this most.