The tails in the show are made by soft stoff. Its very easy to swim in or rather move in, they are using diffenert colers from season to season. In season one they have lime green tails and in season two they have darker green tails. They all bought the tails online from Germany from a girl named Kirstine she is making the tails by herself but togther with some others.
The tails got really popular thanxfully by the3tails and because of H2O just add water.