Did you know that there is a “Unicorn crestfish”? Eumecichthys fiski is a real, though rare species lurking off the coast of South Africa and Australia, 1000 metres deep.
Check out this beauty:

Encyclopaedia Britannica notes that they are “herbivorous algae eaters.” while Fishes of Australia describes their exciting superpower: “As a defence against predators, the Unicorn Crestfish can expel black fluid from around the anus.” Much better than farting rainbows.
For more on this species, check out:
Bray, D.J. 2017, Eumecichthys fiski in Fishes of Australia, accessed 23 Jul 2019, http://fishesofaustralia.net.au/home/species/4329
Davesne, Donald. “A fossil unicorn crestfish (Teleostei, Lampridiformes, Lophotidae) from the Eocene of Iran.” PeerJ 5:e3381; DOI 10.7717/peerj.3381
Froese, R. & D. Pauly (Editors). (2019). FishBase. World Wide Web electronic publication. version (02/2019)., available online athttp://www.fishbase.org
“Unicorn fish.” Encyclopaedia Brittanica. 18 May 2011. Accessed 23 Jul 2019, https://www.britannica.com/animal/unicorn-fish-Naso-genus.