"Look, Mom! What a pretty fish!" said John to his mother. John's mother asked, "Where did you get it, John?" "Frank caught it in the river. I went to the river to get some water and saw this little fish. Then I told Frank about the fish, and he ran to get his fishnet  . He put the net into the water, and caught the fish. I put it into this box," "Well, what will you do with it?" asked John's mother. "I will keep it, Mom," replied John. "But, my boy, it will not live in that box. You should put it back into the river." replied his mother. John felt sad and said, "I wish I could keep it.  It is so pretty! May I put it into the pond?" "No, John," said his Mom, "you must put it into the river. A trout   will not live in warm water." Why can't the fish live in the pond?
Because its mother lives in the river. Because the water in the pond is dirty. Because it can't live in warm water. Because it likes living in a big place.