If you go to a place with water, you can usually count on there being fish around. It's where they live basically. And while we're not sure where this person visited, we are pretty sure this comment was unnecessary. They wrote a review that said, "No one told us that there would be fish in the water. The children were scared". It's certainly fun to imagine someone going to an aquarium and then complaining about there being fish, but again we're not sure what kind of attraction they visited.
We're also not sure why children would be scared of fish as kids are usually the biggest fans of fish out there. However, it might be a good idea to get children used to the idea of there being fish in the world.