|The Lost Mermaid|
|Original airdate||March 25, 2019|
|Previous||Hide and Seek|
|Next||The Star Crystal|
(from an official ukrainian page for the episode)
'Today is a sport's day nearby the lake of Dreams. Rose was helping Bella to make trough the course of obstacles. But suddenly they heard an outcry for help. And when they arrived to the place they were shocked: a mutant was stuck in the sea grass at the lake. But maybe they just were mistaken?' 
There's also russian language version as well and it's almost the same except for the word the lake of dreams is named with, it's another synonym of the word 'dreams'. 
During Gym classes near Dream Lake, Rose is helping Bella get through an obstacle course (apparently set up to practice spell-casting whilst running). After besting several obstacles, they fall down a hill but are unharmed, and Coach tells them to come back for mirrorball. Bella thanks Rose for her helping, saying that she doesn't think she could have managed alone, but Rose tells her she just needs to work on her concentration. Rose then hears Glitterina's cries for help and helps free her from some lake weeds. Upon realising she's a Mermaid, Rose and Bella flee the lake in fright.
Back at Gym class, Coach is updating Principal Sparkle on how the day's going when Bella comes running over, yelling about a mutant Filly. Rose explains that it wasn't as monstrous as Bella suggests, but that it did have a fish-tail. Sparkle realises this must be a Mermaid Filly from Aquatica which, as legend has it, is in the depths of Dream Lake. She looks up the history of the Mermaids and tells them how Wranglum fought them for their Aquamarine crystal, and that the Mermaids disappeared soon after, believed to be lost. Rose instantly wants to help them restore the crystal, but Sparkle tells her not to. As Rose and Bella leave, they bump into Will, who had been spying on them, and he convinces them to try after all.
Rose, Bella and Will decide to take a rowboat to the island the crystal's been left on. Meanwhile, Wranglum, who had been using a raven to spy on them, calls upon his fish minions and Battiwigs to go steal the crystal. The students, with much complaining about the water by Bella, reach an island, and Will and Rose soon find the crystal. They return to the boat, but there Wranglum's fish steal it and the students give chase. They nearly get the crystal back, but Rose is knocked into the water by the sharp-toothed fish and, with the boat sinking, Will grabs Bella and flies to safety.
At the bottom of the lake, Rose awakens in a room to find she has been saved by Glitterina. After reassuring Rose that her friends are safe, Glitterina tells her more of Aquatica's history: their army was losing against Wranglum, but their last warrior hid the crystal to keep it safe. However, they never found the crystal again and, without its magic, the Mermaids are disappearing. The underwater tunnel to Aquatica has been sealed and only Glitterina remains on this side, having failed in her quest to find the crystal. Rose reveals that she and her friends found it, and tells Glitterina she'll get it back for her.
On land, Will and Bella prevent Battiwigs from getting the crystal as they mourn for Rose. Under the water, Rose and Glitterina then see the fish with the crystal and Rose activates it to send out laser blasts, scaring all but one fish away. Upon seeing the laser blasts above the surface, Will and Bella realise that Rose must be alive. Will gets hit by a blast and Bella has to be the one to go into the lake. She reveals that she can't swim, but Will reminds her that Rose believes in her, and Bella finds the strength to try: she dives into the water, fights the last fish, reclaims the crystal, and finds Rose before having to resurface for air.
With the magic of the crystal, Glitterina restores Dream Lake and reopens her way home, Aquatica. The rest of the class realise that something's happening, and come over. Glitterina thanks Rose, who explains that she couldn't have done it without Bella and Will. Coach congratulates them, but says they still need to go to Principal Sparkle's office and explain their disobedience to her.
In the Royal Magic Academy's basement, Battiwigs is listening to Wranglum rant. Battiwigs, believing Wranglum to secretly been lonely, has brought one of the fish minions in a bag, and it promptly grabs hold of the mirror and starts flopping around the room. The episode ends with Wranglum continuing to yell at Battiwigs as his luckless assistant tries to catch the fish.
- This episode's pre-credits sequence is the start of the episode rather than a preview.
- Will flies using his wings several times in this episode.
- This is the first episode where Wranglum has been seen using his mirror to communicate with animals other than Battiwigs.
- Glitterina is mentioned to be from Aquatica even though, in toy canon, she rules over Coralia.
- The Ukrainian description of the episode calls Glitterina 'a lost mermaid' ('Загублена русалка') while the link to that page has a word 'заблукана' in it (meaning 'somebody who wandered off'). It appears the episode's title was changed there. The Russian language title appears to be the second version of the Ukrainian title.
|Italy||Mar. 25, 2019|
|Ukraine||Dec. 10, 2019|
|China (Mandarin)||Nov. 28, 2019 (iQiyi)|
Jan. 30, 2020 (Hunan TV)
Russian: 'Заблудшая русалка'
- ↑ (In ukrainian) "Сьогодні спортивний день на озері Мрій. Роуз допомагала Беллі вивчати курс з долання перешкод. Раптово вони почули крик про допомогу. Але коли вони прибули на місце, то були приголомшені: в озері у водоростях заплутався якийсь мутант. Чи не помилились вони? " 
- ↑ (In russian) "Сегодня спортивный день на озере Грез. Роуз помогала Белле изучать курс по преодолению препятствий. Внезапно они услышали крик о помощи. Но когда они прибыли на место, то были потрясены: в озере в водорослях запутался какой-то мутант. Но не ошиблись ли они?"