The 12 Humboldt penguins at the Sealife Centre in Scarborough, northeast England, were showing signs of stress as they shivered through one of the wettest winters on record.
Although the penguins are accustomed to cold weather in their natural habitat of Peru and Chile, the constant rain has come as a shock to them.
Keepers noticed they were tending to huddle together for warmth rather than plunging into the water.
So it was decided to slip pills into the fish they are fed on a daily basis.
"They are under treatment for stress and we hope the tablets will have a calming effect on them."
Lyndsey Crawford, the centre's display curator, explained that the pills were designed to stimulate normal behaviour in the penguins.
"Hopefully their instincts will kick in and they will realise they are not in any danger," she said.
The penguins have no idea that they are taking pills and suffer no discomfort as a result.
"They literally don't know anything about it. It's a tiny tablet that fits into the gill of the fish. It doesn't taste awful," she said.
Humboldt penguins are threatened with extinction in Peru and Chile due to a range of factors including climate change, the over-fishing of the species that they feed on and problems with becoming entangled in fishing nets.
Prime Minister David Cameron visited flood-hit areas of Somerset today following criticism of his government's handling of a crisis that has left swathes of the country under water.
Royal Marines helped to evacuate the residents of 140 homes in the Somerset village of Moorland after floodwaters rose rapidly overnight.
