Blowfish

Blowfish was a name given to a race of piscine humanoids with faces strongly resembling a blowfish. Emily Holroyd referred to them as Homoformatus piscis. (PROSE: The Baby Farmers)

Biology
The Blowfish were humanoid, but with fish-like faces. They had bright red skin, large crests on their heads and tendrils and feelers around their faces. (TV: Kiss Kiss, Bang Bang, Fragments) Next to the jaws were gill slits, with the sensitive gills inside. They could breathe both water and air and were revitalised with water. They had stinging, yellow sputum. Blowfish were more susceptible to electrical shocks than humans. (PROSE: The Undertaker's Gift) Toshiko Sato's scans of one Blowfish revealed high levels of algae. (TV: Kiss Kiss, Bang Bang)

Culture
Blowfish seemed to have a weakness for human pleasures and on Earth they often committed a wide variety of crimes. (TV: Kiss Kiss, Bang Bang, Fragments) Jack Harkness considered them to be entirely self-serving. (PROSE: The Undertaker's Gift)

History
In 102, the Blowfish were among the races who joined the Alliance. A representative came to Stonehenge and witnessed the imprisonment of the Eleventh Doctor in the Pandorica to save the universe. (TV: The Pandorica Opens) When the plan failed, they were turned to dust and removed from the universe, along with the rest of creation beyond the Earth and its moon. They were restored when the Doctor "reset" the universe. (TV: The Big Bang)

Torchwood Three frequently encountered Blowfish who had slipped through the Rift. They were one of the few aliens who could communicate with humans, though they rarely had much to say. As they were so commonly encountered, the firing range at Torchwood used pictures of Blowfish as targets. (PROSE: The Undertaker's Gift)

In 1899, Jack Harkness was sent by Torchwood Three to collect a young Blowfish. He was brought back to the Hub, but since there was no way to return him home, he was shot dead by Torchwood agent Alice Guppy, which Harkness objected to. (TV: Fragments)

At some point after this, Tiberius Finch and Gertrude Blight, with funding from Sir Henry Montague, started breeding and experimenting on aliens, including Blowfish. When Torchwood investigated, they sent the Blowfish to attack them. Most of the remaining Blowfish were killed when Charles Gaskell blew up Finch's headquarters. Two unrelated Blowfish also learned of these experiments and were brought to Sir Montague by Jack Harkness, where they killed him. (PROSE: The Baby Farmers)

Another Blowfish was in league with the Time Agent Captain John Hart. He also fell victim to temptation, stealing a sports car and embarking on a drug-fuelled joyride through Cardiff. He was tracked down by Torchwood Three. He took hostages to bargain for his release, but Jack Harkness shot him in the head. Despite earlier encounters, the species were not on record at Torchwood prior to this encounter. (TV: Kiss Kiss, Bang Bang)

Gwen Cooper recounted the time when she encountered a Blowfish that got its head stuck in the toilet whilst trying to rehydrate. (AUDIO: Department X)

In 2009, two Blowfish criminals, Kerko and his brother, came to Splott. Jack Harkness tried to capture them, but Kerko's brother was accidentally killed. This led to Kerko having a grudge against Jack Harkness and he refused to cooperate with him. When the Undertaker's Gift was activated and started destroying the Hub, Kerko escaped and tried to kill Jack. Kerko was eventually killed, though the repairs to time by a Vortex Dweller led to him returning to life. (PROSE: The Undertaker's Gift)

A Blowfish observed the Doctor's trial at the Shadow Proclamation, possibly as a member of the jury. (COMIC: Fugitive)

A Blowfish was present in the Maldovarium when Colony Sarff visited the establishment while searching for the Twelfth Doctor on behalf of Davros. (TV: The Magician's Apprentice)

A Blowfish's head was on display in Hedgewick's World of Wonders in the alien collection. (TV: Nightmare in Silver)

Undated events
A Blowfish visited the Fluren Temporal Bazaar. (COMIC: Weapons of Past Destruction)

Alternate timeline
In an alternate timeline in which John Hart took control of the Torchwood Institute and became King of the British Empire, a "fella with a face like a fish" wearing a purple suit took hostages at a Cardiff nightclub, leading the police to request the assistance of Torchwood Three. Arriving on the scene personally, John Hart deemed the alien threat to be beneath him and ordered that the nightclub be destroyed with grenades. (AUDIO: The Death of Captain Jack)

Behind the scenes

 * Introduced in Kiss Kiss, Bang Bnag, the Blowfish were created by writer Chris Chibnall, who was credited for their reprisal in The Magician's Apprentice.