Sam, Sebbie and Di-Di-Di: At the S.E.A. Aquarium - Sam, Sebbie and Di-Di-Di, #2

Sam, Sebbie and Di-Di-Di are three siblings who love doing things together. One sunny Sunday, their parents take them to the S. E. A. Aquarium where Sam and Sebbie suddenly lose track of their little brother. When Sam realises the fish she saw in the tank was not really a fish, but Di-Di-Di, they jump into the tanks and start asking all the fish if they have seen their brother. Finally they find Di-Di-Di with Jay, the Manta Ray.
And they find out Jay has been sad because everyone is too afraid to play with him. So the siblings show all the other fish just how much fun the manta ray can be.