Water Hyacinth is a beautiful plant. But sadly it is a highly destructive invasive species in many places. As you have seen, "they reproduce really fast". When you pass along plants please warn the recipients to keep it in a container and to never, ever, introduce it to open water. I'm actually quite surprised you found it for sale.

Thanks, floral. My friends and I all grow water hyacinth and lotus in containers or tubs. In our area water hyacinth cannot over winter outside. I can’t overwinter them indoor either. But I see it can be a big problem in a warmer area. My friend grow hyacinth in her little pond-tub so her Koi fish can take cover from the birds.

I'm sure you are aware and responsible.

Just so long as none of your pass alongs get repassed and find themselves in warmer climes.