For about 15 minutes Wednesday night the disco music at the Fox-trappe Club stoped and Hoyt Fuller, editor of a serious black magazine, "First World," stood beneath the strobe lights, his plaintive voice replacing the pounding beat of the Bee Gees and Diana Ross.

"I am convinced that in an estimated population of 30 million blacks in this country, there must be at least 100,000 people who want an independent political and cultural journal," said Fuller, who had traveled to Washington from the magaine's offices in Atlanta to make a pitch for the struggling publication.

"Aren't there people who want a unique voice?" he asked? The 100 people who had stopped by the club to support Fuller nodded their agreement.

But the up and down history of "First World" does not reflect that patronage.

For Fuller, 48, the survival of "First spiritual and subject heir to "Negro Digest," which Fuller started editing in 1961. Later it was renamed "Black World." Its original publisher, Johnson Publishing Co. ("Ebony" and "Jet"), discontinued the monthly magazine in April, 1976, citing financial losses. Not willing to let it die, Fuller changed the name and sought the means to keep it alive.

Under Fuller's editorship, the magazine introduced writers such as Nikki Giovanni, Sam Greenlee, Ernest Gaines and George Kent to the public and discussed topics other journals shied away from, such as black-on-black crime.

Since January, 1977, Fuller has been able to publish only four issues, using up his own savings and the piecemeal profits of a series of national fund-raisers. Supporters include Pulitzer Prize-winning poet G w e n d o l y n Brooks, Broadway producer Woddie King Jr., Playright Ntozake Shange, actress Ruby Dee, writer Maya Angelou and politician Julian Bond.

"These small fund-raisers publicize the magazines, get subscriptions and help defray some expenses. But now, in order to continue, I am starting on the larger funding sources," said Fuller.

"The whole situation is precarious but still I am hopeful," he said yesterday after meeting with some foundation representives. "Of course, sometimes I am discouraged. It's lonely in a way and there have been times in the last year and a half that I thought I was personally insane. But I am convinced that this magazine has an audience of individuals who are seriously concerned and interested in what happens to black people in the world."

He disagrees that "First World" has been as much a victim of black apathy as dwindling money sources. Fuller, again optimistic, says distribution and advertising problems have kept people from knowing the magazine is alive. Although the Washington committee sent out 850 invitations, only 100 people showed up, a number some considered good, considering the proliferation of fund-raisers and the absence of a name attraction.

Other programs include no staff (his one full-time assistant had to eave for a paying job; Fuller works gratis) and a major distribution snafu last summer when the New York City distributor went bankrupt. "But", said Fuller cheerfully, "we have the personal interest of a Chicago bank president and we will be eligible for a grant from the National Enowment for the Arts after our sixth issue . . . "By then," he smiles, "we will have proved our seriousness."