Concerned biologists at the Vancouver Aquarium say their new born beluga whale spent "a really active night" playing in her pool while nursing an infection in her tail.

The aquarium staff has been keeping a close eye on the unnamed calf since the weekend after noticing the baby whale had an abscess. It was drained, cleaned and the calf was put on medication.

The president of the Vancouver Aquarium, John Nightingale, told CTV's Canada AM Wednesday it appears the whale is doing much better now.

"Things are going great. The baby spent a really active night -- nursing is good, swimming strongly, (and) spending a fair amount of time playing. In human terms, she looks like she feels better," Nightingale said.

He noted that only a few days ago, the whale had appeared to be moving more slowly. But since staff opened up the abscess and cleaned it out, she has appeared to become "a lot perkier," Nightingale said.

Dr. Martin Haulena, the aquarium's veterinarian, has told reporters that staff members don't know why the beluga developed the abscess. But he said that for most mammals, the first year of life can be uncertain, which is why the beluga is under 24-hour observation.

"Certainly infectious disease, while I wouldn't describe it as common, is certainly something that you watch out for in a newborn animal," Haulena said.

Nightingale noted, "When you're a baby things change quite quickly -- as any new mom will tell you."

He said the baby beluga is still on antibiotics. Staff members have also given her blood tests to make sure the baby whale does not have a more serious infection or problems with her immunity.

The calf was born on June 10 to mother Qila, a 13-year-old beluga. Five belugas born at the aquarium have died. The most recent died in 2005 at the age of three.

Janos Mate of activist group No Whales in Captivity told CTV British Columbia that the aquarium has had too many problems keeping animals alive.

"It has had over six whales and dolphins die after giving birth and the aquarium is not a healthy place for these intelligent beings to live."

Marine biologist John Hall told Canada AM on Wednesday that aquariums are facilities for captivity and "are not the wild."

"So, there are a lot of stresses that are placed on the animals that they may not face in the wild," the former research scientist at SeaWorld said.

He said some whale species have had more success in captivity than others.

Belugas "are a high arctic species and tend not to do nearly as well as, say, bottlenose dolphins," he said.

With files from The Canadian Press