Fledgling little blue penguin's swim therapy an online hit after his rescue from St Kilda Beach

A fledgling little blue penguin found weak and thin at St Kilda Beach recently is doing well at Dunedin's Wildlife Hospital, and video of his swim therapy has proved an online hit.

The young penguin was very underweight and in poor condition when taken to the hospital by Department of Conservation staff, the hospital trust's co-chair Steve Walker told 1 NEWS NOW today.

Mr Walker said it's common for fledgling penguins to be underweight at this time of year, but the feisty penguin is gaining weight and staff are working on getting him more waterproof and fit.

The penguin was initially given a swim in a sink and then progressed to a bigger pool where he's been preening.

"Preening is vital to ensure feather health and enable waterproofing. These guys needs to have perfectly waterproof feathers to protect them from the cold and becoming waterlogged when foraging at sea," the hospital wrote in a Facebook update.

Video of the penguin in the pool, still a little clumsy and occasionally flipping right over when trying to preen, has had 2,400 views. 

Mr Walker said he imagines the penguin will stay at the hospital for another few weeks, and when waterproof and fit they'll be able to release him.

He said the hospital will seek advice from DOC on where to release the penguin, but it won't be back at St Kilda because of how popular it is with people and dogs.

The young penguin is doing well at Dunedin's Wildlife Hospital after being found at St Kilda Beach. Source: 1 NEWS