The sturgeon, named Steve, swam out of World of Water in Romsey, Hampshire when it was inundated by flood water in early February.
But now staff at a car wash a mile from the centre have discovered him in a deep puddle.
A larger koi carp fish named Chadwick escaped at the same time but, despite sightings, has not yet been retrieved.
Centre manager Mark Bradbury said he was "hugely relieved" Steve had been recovered and "only a little worse for wear for his travels."
The seven-year-old fish was used as part of the shop's displays, but Mr Bradbury said similar fish would retail for up to Â£1,000.
"He must have crossed the road and got to the petrol station through the flood water. He's got a few bumps and scrapes but is happy to be back with his friends," he explained.
The centre has now re-opened after being closed for three weeks because of the floods.

The Addicks dropped into the relegation zone following Tuesday's 3-0 defeat at home to Preston.
The 40-year-old has been in charge at The Valley since January.
"I need to worry only about the next game, how I pick the team and how I encourage the squad to bring the result on Saturday," he told BBC Radio London.
Charlton have only won two of their 12 league games this term and Luzon described the defeat by Preston as "a difficult night".
However the Israeli, who previously worked under Charlton owner Roland Duchatelet at Belgian side Standard Liege, says recent injury problems have hampered his team selections.
"We know that we have a crisis with the injuries in the last two months," Luzon said.
"This is the situation. This is our squad. Without a pure wide player in the eleven, it is difficult to create chances and get the result.
"I hope on Saturday some of them will come back and help us to choose a normal eleven with balance. Then we can play football."

A social media campaign had proposed giving Halti mountain summit to Finland for its 100th birthday next year.
The border between the two countries runs up the mountain near its peak.
But Norwegian Prime Minister Erna Solberg said that sadly she had had to turn down the idea because the country's constitution prohibited any sacrifice of Norwegian territory.
Part of Halti mountain is already in Finland - and forms its current highest point - but the peak is 20m (66ft) across the border inside Norwegian territory.
Campaigners had proposed moving the border to give the summit, at 1,330m (4,363 ft), to Finland, saying the change would be barely visible on the map.
They had argued that the peak "would be a wonderful gift to our sister nation" to mark its independence from Russia, and not a big loss to mountainous Norway, which has much higher peaks.
The campaign's Facebook page got 17,000 likes, with support from both sides of the border.
But it hit upon an insurmountable legal issue.
"Border adjustments between countries raise challenging legal problems, among them linked to the Norwegian constitution," Ms Solberg wrote to Svein Leiros, the mayor of the town of Kaafjord in northern Norway, who supported the campaign.
Norway's  1814 constitution stipulates that the country is "indivisible" - and apparently not even an area the size of a football pitch can be split off.
"We will instead consider another suitable gift to Finland on its anniversary," the prime minister added.
A metre-long fish that escaped from an aquatic centre during recent flooding has been found.
[NEXT_CONCEPT]
Charlton Athletic head coach Guy Luzon is not concerned about his future despite a run of eight games without a win in the Championship.
[NEXT_CONCEPT]
Norway has rejected a plan to give its neighbour Finland a mountain to mark the centenary of its independence.