''The tuna fish is on the second shelf, left,'' said Aunt Dee. ''Get me down two cans if you don't mind.''

I reached up and extracted two cans, one larger than the other, from Aunt Dee's neatly arranged closet.

''No, no!'' she exclaimed. ''They both have to be the same size. Get me another small one and put back the big one.''

I did so, asking, ''What are you going to do with the tuna?''

''My club, the LCA, is starting a new activity,'' she answered

I had heard of the LCA, ''Ladies of a Certain Age,'' frequently before. They met bi-weekly, to engage in such projects as book reviewing, volunteer reading at the children's room in the library, and reporting on the latest movies. ''Tuna fish?'' I asked. ''Are you starting a cooking class?''

''No. We all know how to cook. Some not so good,'' she added.

''You're preparing a luncheon?'' I tried again.

''No. We can't have home made lunches. We never know how many of the 20 members will show up, what with doctors' appointments, and special diets, and visits of children,'' she answered.

''So what are you going to do with the tuna fish?''

''We're starting an aerobics class,'' she said. ''I know I still have my girlish figure, but one has to be careful.'' Aunt Dee did, indeed still have the buxom figure she had had as far back as I could remember, which was the style when she was a young woman. She often sneered at the ''skinnymarinks'' who were now the fashion.

''I still don't get it,'' I confessed. ''Why the tuna?''

''We hold one can in each hand, like weights, and do exercises,'' she explained. ''When we build up strength we graduate to cans of chicken soup.''