Virtual Villagers - The Lost Children. HELP?

There are algae eating fish in the diving pool, but I can't remember what step you take to get there? But there algae eating fish in the diving pool for sure! Take your villagers over to it and drop them in to look for them? You might have to take them to the algae first and then take them to the diving pool? Been a while since I played it? I have the other two games as well.