Doomwatch - The Battery People (1970)
In a way this episode which turned out to be rather sinister reminded me a little of the 1972 film.
With an outcome which was rather creepy, the story involved the Doomwatch team investigating a fish farm in North Wales which it turns out is producing boneless fish due to chemical agents in the water. Come the end it wasn't just fish which had no bones. Nicely acted with good location work and vomit inducing sequences of battery chickens not to mention cock fighting, this episode shows why the series holds a BBFC 15 certificate.
This series is just getting better and better.