Fishtronaut: The Movie
Peixonauta - O Filme (original)
Fishtronaut, Marina and Zeek travel to the big city in search of Grandpa, only to find that everyone else has mysteriously vanished too.
Starring Celso Alves, Fernanda Bullara, Fábio Lucindo
It's a animation and action & adventure movie, and has a rating of 7.7 out of 10 from Imdb which is usually fine for this kind of movie.
Watch it here
Not found streaming from Austria.