No question the little boy is cute and all, but as a parent if you don't get a handle on saying "NO" to your child it only makes things worse in the long run.
Sure you want to explain logically why you can't keep a fresh water fish as a toy. This issue I have is as you debate with this child the fish is out of water for like 2 minutes. Basically suffocating the fish to a terrible death. Imagine if it were a dead bird he found...is he still cute? Better yet, what if he picked up poop and wanted to keep that as a toy?
Think about it and watch video again. What do you think?