Their brightly-coloured skin and beautiful fins have made them a favourite pet.
But woe betide anyone who releases their guppy fish into the wild for these tropical creatures can upset the other inhabitants of British rivers and streams.
Researchers from the University of St Andrews, in Fife, have found that a lone female can create an entirely new population.
Taking the plunge is easier than it might seem, with a range of enticing locations where you can learn the basics of scuba diving, from Red Sea resorts to idyllic Indonesian islands. Matt Barr explains
I have kept various aquariums (freshwater, marine and planted aquaria) for over 40 years. This blog, though not often very personal in tone allows me to explore the latest findings, articles and styles of aquarium keeping from around the world. I hope it communicates my love and interest in aquarium keeping in all its diverse forms and inspires a few ideas in others.