A zoo manager was sacked after selling monkeys so he could create a menagerie of exotic animals, a tribunal heard.
Mr Riley barricaded himself in his flat with turtles and a wallaby
Stephen Riley, 48, barricaded himself in his flat with a wallaby and turtles after he was dismissed from Tropiquaria in Somerset in January.
He won a claim for unfair dismissal on Wednesday because the zoo had not fully investigated before sacking him.
But the tribunal also said he should not get any compensation because he had been guilty of gross misconduct.
Mr Riley said he was called to a meeting with his employers in January this year, but was not given a chance to explain his actions and dismissed.
He stormed out of the meeting and barricaded himself inside his flat on the zoo grounds. He was evicted 23 days later on 6 February.
Mr Riley who worked at Tropiquaria for two and a half years, said he planned to start his own zoo in Spain, where he now lives.
His collection included rare snakes, a tamarind monkey and a meerkat.
Staff noticed the number of marmosets dwindling
The zoo's managing director Stephen Smith told the employment tribunal in Exeter that staff became suspicious about the number of animals Mr Riley had been bringing to the zoo.
They also noticed that the number of marmosets had dropped, some of which Mr Riley had sold to North Cornwall Aviaries.
It was also claimed he tried to sell a tapir that was owned by the zoo.
A representative for Tropiquaria said Mr Riley had traded animals with other zoos to build up his collection, although paperwork showed they did not belong to him.
Mr Riley said he had collected the animals with his employer's approval.
The tribunal rejected Mr Riley's claim for compensation after concluding that he was guilty of gross misconduct.
"We unanimously concluded that the claimant's conduct over the sale of marmosets and the attempt to sell the tapir which was not his to sell amount to gross misconduct for which the respondent could reasonably have dismissed the claimant summarily."
This meant that any compensation should be reduced by 100%, the tribunal said.