Miley Cyrus has written a song about her dead fish.

The 22-year-old singer, whose pet blowfish Pablow died in February, broke down in tears while performing the track she wrote about him during her latest Backyard Sessions showcase.

Dressed in a unicorn onesie, the 'Wrecking Ball' singer, who posted a video of the emotional performance on Facebook, poured her heart out in the lyrics, singing: ''Why does everything that I love have to die? If I could do it again, I'd release you to sea because I can't bear to see someone so wild just die in a tank.''

Miley, who got a tattoo of Pablow three months ago, was previously devastated after her dog Floyd was killed by a coyote in April 2014 and blamed herself for his death.

In a lengthy post about her grief on Twitter at the time, she wrote: ''I don't know when the regret and the guilt will fade. I don't know if it ever will.

''I feel like I let my boy down. My job was to protect him and I'm not a person that takes failure lightly...Today is one of those days where I can't open the curtains to see the sun...open the windows to hear the world going on around me because to be honest I hate the fact that the world's still spinning. I want it to stop...I want everyone's heart to break the way my heart is breaking.''

She also honoured the late Alaskan Klee Kai by getting a tattoo of his head inked under her left armpit.