This show has a surprising number of fans in Europe, which begs the question why no TV station wants to air the show anymore.
This show is also very popular in Taiwan, to the point that there's more Mermaid Melody merchandise there than it's native Japan nowadays.
The series is specially loved in Spain and Italy, where it is actually better remembered than more successful magical girl series like the mighty Futari wa Pretty Cure. The former is particularly notable by the sheer effort it was put in adapting the series, giving it a better than average dub for an anime and bringing professional singers to perform the music themes.
Harsher in Hindsight: One thing no one wanted to talk about when the series aired. The entire plot — both the villains' plan and the Lucia/Kaito love story — starts because of a tsunami in the Indian Ocean, which killed Kaito's parents and destroyed the orange mermaid country. A certain real-life tsunami in the Indian Ocean with a similarly high death toll happened the day the anime ended.
While significantly good overall, the Spanish dub sometimes has a hard time trying not to fall in Totally Radical. The teenage lingo used for the dialogues was a bit outdated even by the time they distributed the anime in Spain, not to mention when one watches the series nowadays.
Moe: Seira is a beautiful little Orange mermaid that certainly steals the fanbases' heart.
In fact, All of the Mermaid princesses, like Lucia Nanami, If not the entirety of "The Mermaid Melody" team. They all have their own way of being Adorable.
Snark Bait: Has this reputation among many modern manga readers, due to the similarities it has to something you'd see on DeviantArt.
Squick: Some see the fanservice as this, considering the series is still technically aimed to little girls, and most of the characters are around 13.
Strangled by the Red String: Caren with Subaru, an anime-only character probably introduced only so people would stop slashing her with her sister.
Suspiciously Similar Song: Some European dubs utilize a limited repertoire of songs for several characters. For instance, Lady Bat and the Black Beauty Sisters share songs in some of those versions.
That One Boss: "Aurora no Kaze ni Notte" in the video game Pichi Pichitto Live Start.
Viewer Gender Confusion: Lady Bat, although officially male, causes a lot of confusion between fans. Probably justified (and probably invoked) because he's also a crossdresser.
What Do You Mean, It's for Kids?: The more suggestive and bloody manga is rated "13+" in North America, where the Animation Age Ghetto compels manga publishers to put ratings on their books, yet it was originally published in Nakayoshi, a magazine for little girls.
The Italian dub. The voice acting is great, and the songs are possibly better than the Japanese ones. They completely substituted J-pop music for pop-rock and rewritten the lyrics to match the new song. Checkitoutyourselves.
In particular, the song "Assoluto Amore" (lit. "Absolute Love"), the replacement for "Return to the Sea", manages to capture Sara's character perfectly, being an ode to The Power of Lovesung to an angry melody with restrained anger and, near the end, subtly warning it can destroy the world.note the lyrics are "L'Assoluto di un Amore può/cambiare i connotati al mondo". Literally it translates to "The Absolute of a Love can/change the world's face", but "cambiare i connotati" is usually an euphemism for "busting someone's face".
Some countries made Noel's color Indigo, as Aiiro (Deep-Blue), would be hard to translate, and make her too similar to Hanon. Technically, Hanon is aquamarine/turquoise, and not blue, but this often had to be changed too.