While most other retail chains were reporting strong sales and prospects for a record Christmas yesterday, the Neisner Brother chain filed for bankruptcy in Rochester, N.Y.

Neisner - which runs a large variety store on G Street in downtown Washington - filed a petition under Chapter XI of the Bankruptcy laws, saying it could not pay its bills on time.

Under Chapter XI, a company continues to operate but is protected from its creditors while it attempts to restructure its business.

Neisner said it has assets of $59.9 million and liabilities of $46 million. For the six months ended Oct. 8, the company lost $2.6 million on sales of $87.9 million.

Company president Fred Silverstein said Neisner's is "prepared to continue normal operations during the upcoming holiday season and for the foreseeable period thereafter."

In a terse announcement, he did not discuss whether the chain would close stores, a step virtually always taken when a retailer files under Chapter XI. The Neisner variety and Big N discount stores are scattered across the Northeast, in many cases not concentrated heavily enough in markets to maximize their penetration.

Long run by members of the founding family, the Neisner chain was one of the slowest of the "five and dime" operations to move into higher-volume higher-profit discount stores.

It continues to draw most of its business from variety stores after Woolworth switched its growth to Woolco stores and S.S. Kresge's discount operations became so predominant that the company changed its name to K mart Corp.