Blowfish

Blowfish was a name given to a race of piscene humanoids with a face strongly resembling a blowfish. Emily Holroyd also referred to them as Homoformatus piscis. (TWN: The Baby Farmers)

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

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

History
In 102 A.D., the Blowfish were among the races who joined the Alliance. They came to Stonehenge and helped imprison the Eleventh Doctor in the Pandorica in order to save the Universe. (DW: 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 returned when the Doctor managed to "reset" the universe. (DW: 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 the 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. (TWN: The Undertaker's Gift)

In 1899, Jack Harkness was sent to collect a young Blowfish by Torchwood 3. He was brought back to the Hub, but since there was no way to return him home, he was simply shot dead by Torchwood agent Alice Guppy, which Harkness objected to. (TW: 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 started to investigate, 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. (TWN: The Baby Farmers)

In 2008, 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 in order to bargain for his release, but Jack Harkness shot him in the head. (TW: Kiss Kiss, Bang Bang)

Later, in 2009, two Blowfish criminals, namely Kerko and his brother, came to Splott. Jack Harkness tried to capture them, but during the attempt 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. (TWN: The Undertaker's Gift)

A Blowfish was observing the Doctor's trial at the Shadow Proclamation, possibly a member of the jury. (IDW: Fugitive)