Supporters of live music fear the UK's scene will collapse without government support.
The lockdown has left 140,000 performers, agents, promoters and technicians without a steady income since the end of March.
About 82% of the UK's live venues are now at risk of closing before the end of the month, according to an industry survey.
Chief executive of UK Music Tom Kiehl said the effect was "catastrophic".
While major artists continue to make money through record sales and streaming during the lockdown, an estimated 100,000 musicians rely on extensive tours of smaller venues and festivals to provide their income.
A recent survey by the Music Venue Trust (MVT) has found 554 of its 670 member venues are under threat of "imminent closure" as a result of Covid-19.
Leading ticket site Ticketmaster shows more than 1,000 music gigs were cancelled in the first two weeks of May.
Many concert bookers, promoter and agents - most of whom rely on commission from paid gigs - have seen their usual means of income vanish.
Bodies such as UK Music are among those now calling on the government to deliver a support package to the industry in line with other countries.
Among them, Germany is in the process of rolling out a 54bn Euro stimulus to its creative economy.
"In a typical year, live music contributes £1bn to the UK economy and supports many jobs," said Mr Kiehl.
"What we are seeing now with the changes and social distancing likely to continue this year - at least £900m could be wiped off the sector.
"It's impossible to understate the catastrophic effect this is having."
Some six million people attended small and medium-sized gigs last year across the UK.
But venue operators fear they will struggle to attract those audiences again when lockdown lifts.
The Tees Music Alliance runs The Georgian Theatre in Stockton-on-Tees, which has played host to The Arctic Monkeys and The Wonder Stuff in recent years.
But it has had to launch a crowdfunding project to see it through the current period.
Its operators hope to raise £25,000 or reduce their work promoting grassroots music in the North East.
The venue is one of many around the country, including the Bedford Esquires to launch an appeal on Crowdfunder.
Chief executive Paul Burns said venues cannot make any firm financial plans until the government issues advice on how they can operate post lockdown.
He said: "The question is: what will the gigs look like when we do reopen the doors?
"Where we would have had an up-and-coming indie band on tour, the place would have been full of fans jumping up and down.
"Do we put everyone on tables? Do we only allow people that live together to sit together? Do we blank out seats to keep people two metres apart?"
Venues are already offering live-streamed gigs that people can watch from home but the challenge, Mr Burns says, will be to offer them at a quality for which people will pay a ticket price.
Many will need investment to buy the equipment needed for broadcast.
Aside from government support, there are moves to raise money for venues nationally.
The MVT has gathered £1.2m towards its Save Our Venues campaign in little over a fortnight, as some 11,000 people and organisations have donated.
Without help though, the UK's breeding ground for talent is at risk of collapsing, according to the trust's chief executive Mark Davyd.
"This network supports around 100,000 musicians," he said. "If you remove 82% of capacity, you have to remove 82% of places musicians have to perform.
"It would leave us with no sustainable tour circuit.
"It's a very important part of 'brand Britain'. The next 20 years relies on us getting this right."
Venues in major cities, with higher rents and rates, may need the greatest share of support, he said.
Those in the capital in particular are less likely to fall below the £50,000 rateable value threshold that would entitle them to a government grant, according to Mr Davyd.
"We have a jazz club in London that has 120 capacity," Mr Davyd said. "But its rateable value is around £70,000. The same venue 30 miles north of the capital would be valued at £15,000."
Mr Davyd said a support package could include a fund for landlords of culturally-important buildings.
Around 62% of the liability facing venue operators at present is rent, he said.
Without the ability to play in front of a live audience, many musicians are having to drastically change their financial plans for the year.
Though many are coping by offering subscriptions on the Patreon website.
The US-based platform allows fans to pay a monthly fee to access their favourite act's creative process, bespoke live-streamed shows and tuition.
Among those using it is multi-instrumentalist Beardyman - AKA Darren Foreman.
The 36-year-old is known as one of the world's best-known beatboxers and appeared on Fatboy Slim's hit single Eat, Sleep, Rave, Repeat.
He is using Patreon to supplement his income, which has been hit by having had to cancel a spring tour.
"We have seen our work evaporate overnight," he said. "But people like me are lucky. I have produced enough stuff now that there are people out there willing to help when they hear I am in financial hardship.
"They want to keep a roof over my head and they want me to keep doing what I'm doing.
"It won't replace my income entirely but it has helped to keep me going."
Beardyman offers supporters perks through his Patreon page including personal live sets and tours of his home studio. Currently he is releasing a new single every week under his Sheer Volume project.
Founder of the site, musician Jack Conte, said the number of musicians using it in the UK has risen by 200% since January.
"So many people have had this model that's been working for them for so long - but now the world will look very different for quite a long time," he said
"If you can embrace that change and view this as an opportunity to finally get that online following, you are going to make it through this period."