Prosecutors said Bowornbancharak and Bawornban were aware their offer could not be fulfilled.
"It was impossible to sell such high-quality food as advertised," they argued in court, adding that the defendants "didn't [intend] to fulfil the conditions as advertised to the public".
In March, the company – Laemgate Infinite – announced its closure, claiming it couldn't get hold of enough seafood to meet demand, sparking complaints from hundreds of disgruntled customers against the company and its co-owners for fraud.
The pair were arrested on charges including defrauding the public through false messages, and were found guilty on 723 counts on Wednesday and sentenced to 1446 years in prison.
But after Bowornbancharak and Bawornban pleaded guilty, their sentences were cut by half to 723 years each.
It's not uncommon for those found guilty of fraud in Thailand to be sentenced to long terms in prison, but Thai law limits jail time for public fraud to 20 years.
Laemgate Infinite was also fined 1.8m baht ($90,188) and the pair and the company were ordered to refund 2.5m baht ($125,225) to the victims.