Mermaid Heel is known as an all-female guild, with the entirety of its shown members being females. Millianna confirms this when she responds to Erza's question, about if Shô and Wally are in the guild with her. She says" What are you talking about? Mermaid Heel is a guild limited to women."  When Hibiki Lates jokingly said that he would have joined Mermaid Heel, Toby Horhorta angrily commented that the Blue Pegasus Mage "is way off their theme".
The guild's location, aside from it being in Fiore, is as of yet unknown.
Mermaid Heel appears to be a considerably powerful guild, whose team for X791's Grand Magic Games made it 6th out of eight squads completing the preliminary event "Sky Labyrinth", which had 105 other competing guilds disqualified. Such an achievement is made more notable by the fact that one of the teams they managed to outrun, representing Fairy Tail, formerly the strongest guild in Fiore, and counting strong individuals such as S-Class Mage Erza Scarlet and S-Class candidates Natsu Dragneel, Gray Fullbuster and Elfman Strauss, made it only 8th during the preliminaries, barely gaining a place to take part in the real Games. Most of Mermaid Heel's power and reputation seems to stem from its strongest Mage, Kagura Mikazuchi, who has been described as being on the same level as Erza Scarlet, one of Fairy Tail's S-Class Mages, as well as the guild's most powerful female member.
- ↑ 1.0 1.1 1.2 Fairy Tail Manga: Chapter 267, Page 12
- ↑ Fairy Tail Manga: Chapter 281, Page 10
- ↑ Fairy Tail Manga: Chapter 267, Page 15
- ↑ Fairy Tail Manga: Chapter 266, Page 6
- ↑ Fairy Tail Manga: Chapter 266, Page 20
- ↑ Fairy Tail Manga: Chapter 280, Page 6
- ↑ Fairy Tail Manga: Chapter 281, Page 18
- ↑ Fairy Tail Manga: Chapter 14, Page 13
|Legal Magic Guilds||Fairy Tail • Lamia Scale • Blue Pegasus • Quatro Cerberus • Titan Nose • Twilight Ogre • Sabertooth • Mermaid Heel • Raven Tail • Phoenix Grave • Hound Holy • Gramlush • Carbuncle|
|Independent Guilds||Crime Sorcière|
|Other Guilds||Southern Wolves • Love & Lucky|
|Former Legal Guilds||Phantom Lord • Cait Shelter|
|Balam Alliance||Grimoire Heart • Tartaros|
|Dark Guilds||Naked Mummy • Death's Head Caucus • Dark Unicorn • Harpuia • Red Hood|
|Former Dark Guilds||Eisenwald • Oración Seis • Ghoul Spirit • Raven Tail • Reborn Oración Seis|
|Edolas Guilds||Fairy Tail (Edolas)|