andye, I did consider that exact species of fish, but based on a decade of breeding experience, ruled it out as "dangerous."
A guppy? Dangerous?!
Ok, allow me to qualify - and to note that my classification is based on P1R's statement:
A single guppy in a tank is a safe pet. More than one, when there is a male present, and they are dangerous. Now I don't mean dangerous in a physical sense - being bitten by a guppy is amusing - but in a psychological manner to the well-being of a child (and some adults, it seems).
Male guppies are very aggressive, sexually. Very. If a female won't respond to his advances, he will eventually become a physically abusive serial rapist...
Ok, you and your child have - hopefully - survived breeding with psyche intact, now it's time for live births. As I'm sure any parent will tell you - I'm childless - birth is a beautiful thing and now you have 30 more fish, so...
Let the cannibalism begin!