The blaze aboard the 8,000-tonne whaler has raised concerns about environmental damage and threatened to cut short the Japanese whaling fleet's controversial hunt in the Southern Ocean.
"Everything is hunky dory at the moment and we want it to stay that way"
New Zealand officials and environmentalists have expressed concern that the whaler could threaten the Antarctic's biggest penguin rookery at Cape Adare, about 175km away.
The ship is carrying hundreds of thousands of litres of oil and has no engine power.
The environmental group, Greenpeace, has a vessel in the area but its offer to tow the Nisshin Maru out of Antarctic waters has been rejected by Japan as "irrelevant".
Steve Corbett, a New Zealand rescue official, said that the Nisshin Maru was now on an even keel after the crew pumped out the water used in the firefighting effort overnight.
"Everything is hunky dory at the moment and we want it to stay that way, but we can't be guaranteed it will stay that way," he said.
"It is extremely unlikely they will be able to restore full power."
The Nisshin Maru was secured to two other Japanese whaling vessels but they would have limited control if the seas rose, Corbett said.
The New Zealand government, which is responsible for rescues in the region, wanted the stricken ship towed north away from the Antarctic coast.
Corbett said there were "diplomatic efforts" to have the vessel removed from the area.
Japan has said it may have to abandon this season's whale hunt because of the fire, but added that the other whaling vessels could provide any help needed.
Japan says its annual whale hunts, begun after the international whaling commission imposed a global ban on commercial whaling in 1986, are for research.
Environmental groups say the hunts are a pretext to keep Japan's tiny whaling industry alive.