What is the name of this mermaid movie?

I've been trying to remember the name of this mermaid movie I watched
when I was a kid and can't for the life of me. It was about this girl
who took a cream from her parents office (they were scientists). The
cream was supposed to make one a better swimmer. So she goes to a pool
party and uses the cream before swimming. Another girl sees her and
uses it when no one can see her. They both turn into mermaids and
eventually end up kidnapped and exhibitioned in an aquarium. Then the
family of the girl whose parents made the cream have to go rescue the
two girls from the aquarium. I also remember the girls were chilling
in a hot tub when they were kidnapped. Can anyone recall the name of
this movie? It's been driving me nuts that I can't remember the name
when I remember the whole film. Thanks!