THE NATIONAL AQUARIUM is going under fast. Congress is scheduled to vote tomorrow on a compromise resolution that would close the 108-year-old facility and put its fish up for bid. The aquarium could close its doors as soon as Nov. 22. As the budget ax falls around town these days, the aquarium, which is not large enough to be a truly national facility, seems like an awfully small fish for the government to be bothering about. But having an aquarium in the capital was always fun for tourists, and even if its $300,000 budget is done away with, it will still cost the government at least $1 million to convert the fish tanks at the Commerce building into office space.

To keep a truly "national" aquarium in Washington, the Senate had proposed that $500,000 be given to the Smithsonian, proprietors of the National Zoo, to begin construction of an aquarium at the zoo. That idea died in the House-Senate conference. The House had proposed that the aquarium be given to the Smithsonian to be run without any added funds, but that plan, too, fell through in the conference. What remain are rumors of promises that in the future money will be made available for an aquarium that is truly national, unlike the beautiful one in Baltimore, which is the "National Aquarium" in name only.

Here are two proposals for keeping the aquarium. First, if it were allowed to charge a $1 fee for adults --allowing children and school groups to enter free of charge--it could be self-sufficient, according to its director, Craig Phillips. A second possible solution could take place simultaneously. The Smithsonian should start building its own aquarium at the zoo and take the aquarium's specimens when the new quarters are complete. The Senate and the House could help with this plan by replacing the $500,000 that the Senate had orginally intended to give the Smithsonian to help it begin planning its aquarium.