Throughout childhood and into high school, they laughed at Chris Silva, the swimmer. Black kids don't swim, his friends told him.

But Silva was too busy swimming laps to listen. By the time he had become one of UCLA's best swimmers two years ago, the teasing had stopped. Silva's biggest boosters now are basketball and football players back home in southern California.

And tonight, certainly they were cheering long distance when Chris Silva, 21, became the first black swimmer to represent the United States in international competition, assigned the third leg of the men's 4x100 meter freestyle relay at the World University Games. The U.S. was second by .1 of a second to the Soviet Union, which won in 3:21.72.

"It's been a long time coming," Silva said of his distinction. "I guess it's better late than never."

"I've had 15 years to get used to it," he said. "Seriously, the issue comes up a lot. I'm asked if I'm treated any differently than the other swimmers. And the answer is no. Everybody in the swimming community knows me, even if the general public and media are just becoming aware.

"No, there's no special pressure. I don't think about it. I'm here to race and swim. When I line up, I know I'll be representing not only the United States and UCLA, but the black community as well. But when it all comes down to it in 1984 (the summer Olympics), they won't want to know whether I'm the fastest black swimmer, just whether I'm the fastest."

Silva, from Menlo Park, Calif., is very expressive. He knows why his situation is a rarity and seems to appreciate the opportunity.

"Swimming is a sport like tennis and golf," he said. "They cost a lot of money, and not that many black families can afford it. The sport doesn't really produce money for the competitors. It's not a sport in which you can become a Reggie Jackson or a Dr. J and then reap financial rewards.

"The football players I used to run with in high school used to tease me," Silva said. "We'd go out and shoot a few baskets, and if I hit four or five shots in a row, they'd get a little upset and say, 'Okay, let's go to the football field.' And I'd say, 'Fine, then let's go to the pool.' "

Finally, Silva got his friends to come to the pool, to see him in a water polo match at Menlo Atherton High School. It wasn't the "sissy sport" they expected. Pretty soon, more and more of Silva's friends started showing up to watch him compete. "I'd have kept going anyway," Silva says, "but it was great once I got that respect."

He remembers being 4 years old and "bugging my father to take me swimming . . . I don't know why, though." He took Red Cross lessons at a YMCA, then started swimming competitively at age 5. The intense technical lessons came at age 9, and three years later, Silva was hanging around American Olympic hero John Naber at Ladera Oaks.

Two years ago, as a sophomore at UCLA, Silva helped set an NCAA and American record in the 400-meter freestyle relay. He is calling this summer season "a chance to regroup."

"I had a poor junior year," Silva said. "I had to order some priorities. It came down to cracking the books and staying in school, basically. Now, I want to pull myself together and perform well enough to make the '84 Olympic team.

"This (tonight's race) will tell me a hell of a lot; whether I can take the pressure of an international meet," he said earlier today. Can I meet world competition and handle it?

"And then I want to concentrate my senior year on reaching my potential. I have yet to put in a year of seriously hard training. I've sort of abused the talents I've been blessed with.

"But right now, my thoughts are that of any other American--black or white," Silva said. "I want to beat the Russians so bad. It's just like wanting to beat USC."