The 2015 Pan film is another take on giving a backstory to the infamous Peter Pan, and since the majority of the film takes place on Neverland, there have to be mermaids.
In this case, while Peter, Tiger Lily and Hook are on a raft in search of the fairy kingdom, Peter accidentally falls overboard when a crocodile attacks. He is saved by three mermaids (all played by Cara Delevingne) who recognize Peter's special nature and zap the crocodile, sending it away. These mermaids have wispy bioluminescent tails and seems similar to electric eels, not only in their abilities but also in the way that they swim. The entire sequence appears to be CGI, so it has a very dreamlike feel.