Developers behind plans to create one of the world's largest freshwater aquariums in Bedfordshire have rejected a loan to salvage the project.
The project would be four times larger than the Eden Project
Bedfordshire County Council agreed to loan another £300,000 to Nirah, which has already received £3m.
This was on the condition that the company changed its business plan.
The board of Nirah Holdings Ltd unanimously rejected what it described as "a red tape-bound offer" and appealed to the public for support.
The money is needed to finish work for an outline planning application.
The National Institute for Research into Aquatic Habitats (Nirah) wants to build the development on the site of a former brick works at Stewartby.
The research complex and aquarium would be four times larger than the Eden Project in Cornwall.
City financier behind the Nirah project Peter May and Bedford Mayor Frank Branston launched a public appeal for the "Founders of Nirah" to raise £300,000.
Mr Branston said: "This is the last chance for us to bring this fantastic science, conservation and leisure project, complete with thousands of jobs and millions of pounds, to the area."
A Founders' Appeal marquee will be staged at the Bedford River Festival this weekend where hundreds of thousands of people are expected to attend.