Last night's "Trout" Quintet was the climax of the three-day "Schubert, Schubert, and Schubert" festival at Gaston Hall that brightened this weekend in Washington. That winsome, beautifully crafted, superbly lighthearted work tends to dominate any program it occupies. Last night it was performed splendidly, with technical precision underlying its air of relaxed, rather playful conversation among friends.

It was perfectly Viennese in spirit, although only 60 percent of last night's five performers--violinist Eduard Melkus, cellist Hubert Koller and pianist Claus-Christian Schuster--were from Vienna. Their two colleagues for the evening were violist David Becker of the Universiy of Miami and double bassist Robert Dodelin, who played in this season's superb Terrace Theater orchestra for the Washington Opera. They both fit perfectly into the ensemble's style and spirit. As always, the music sparkled, particularly in the variations movement, but not a single moment was less than delightful throughout its heavenly length. It was the perfect way to end a festival and it inspired a substantial part of the audience to a standing ovation.

The Quintet was the second form of Schubert's "Trout" heard last night. At the beginning of the program, soprano Ute Jahr sang the little song about a crafty fisherman and a not-very-clever trout, which Schubert borrowed as a theme for the quintet. Jahr sang six songs in all with a clear sense of their poetry and with a lower register that was warm in tone and well controlled. But her upper register lacked focus and richness, and sometimes the music sounded labored. Pianist Ruth Ann McDonald performed expertly.

In the shadow of the "Trout," the remainder of the program (the Violin Sonata in G Minor and a set of German Dances for piano) was interesting but only occasionally compelling.