Officials said they did not know yet the fate of the thousands of fish contained in the 1.2 million-gallon tank, a popular tourist attraction in Hirsthals, 170 miles north of Copenhagen.
``The flames are still engulfing much of the building,'' Mayor Knud Stoerup said. ``We don't know whether the fish tank and the thousands of fish can be saved.''
Martin Riis, a spokesman for the North Sea Museum, told Denmark's TV2 that the 18-inch-thick glass had apparently held.
The museum was closed for cleaning when the fire broke out shortly after 6 p.m. The cause was not known.
The museum, which had been scheduled to reopen after Christmas, averages nearly 280,000 visitors annually.
Most come to see the $16 million Oceanarium, which opened in 1998. The elliptical, 26-foot-deep tank features thousands of herring, mackerel, garfish and horse mackerel found off the coast of Denmark.
The museum, which itself dates to 1984, also serves as a research center.
On the Net: http://www.nordsoemuseet.dk/gb/default.asp
