The Lambkin and the Little Fish
The little boy is young and innocent, when he is turned into a fish he is sad because he doesn't get to see his sister anymore. The little girl is also young and innocent, she is turned into a lamb and she is so sad that she can't talk to her brother anymore she can't even eat a blade of grass.
Be careful who you trust but when you find the right people make sure to stay happy. In the story the little kids trust their step mother and she turns them into a lamb and a fish, so they shouldn't have trusted her, then the cook and the old woman help them and change them back, they should trust those two.
Strangers came as visitors
In this fairy tale a group of children are playing in the meadow when their mean step mother, who knows witchery, turns her children into animals, the girl into a lamb and the boy into a fish. When visitors come the step mother tells the cook to go get the lamb and kill it for supper, when he gets it back to the kitchen he realizes that it is the little girl and that the woman had turned her into a lamb. He then realizes that the little boy is a fish, and that fish is swimming up and down the creek trying to talk to the girls attention. So he goes and gets the fish and takes him to another woman who knows witchery and turns the lamb and fish back into children and they live with the old woman and never go back to their old house.