My son's pet turtle

Today was an interesting day today. My son has this pet turtle. He had it for about 7 months now. (We take care of it more than he does.) Oh by the way my son is 7 years old. This is a current picture of him. Anyway, we clean the turtle tank out today. We got him some fish to add to his tank. Let me explain that first that we thought giving our son a turtle was better for him to have for a pet than a dog because of our small apartment and that it is less work to do to keep up with the turtle. Anyway, after we clean the tank out and put everything back in it, but the turtle, we added the fish to that tank. Now we have an aquatic turtle that eat fish and other things. Personally, I never saw it eat the fish, the fish always just disappeared. Well that was going to change today. There were 10 fish. There was one really big goldfish that was in the group. I thought that that fish was TOO big for the turtle to eat. As soon as I put the turtle in the tank, it went for the big goldfish. The turtle attacked that goldfish just like a shark attack it's food. It tore it apart! It ate all the pieces too. I never saw anything like that except on TV. My son, of course, thought that was the coolest thing. Well, now we only got 8 fish. I can barely look at the tank now because I really do not want to see that event happen again! You would think that I would be find because I am in the medical field but that was far from surgery or emergency issues!