Seafood - End and The Alternative Karma Consequences

"Monks, these four types of kamma have been directly realized, verified, & made known by me. Which four? There is kamma that is dark with dark result. There is kamma that is bright with bright result. There is kamma that is dark & bright with dark & bright result. There is kamma that is neither dark nor bright with neither dark nor bright result, leading to the ending of kamma.

https://www.accesstoinsight.org/tipitaka/an/an04/an04.235.than.html

Considering the above Sutta, It appears this person has done both dark and bright kamma. The only way he will be totally free from his bad Kamma is when he became an Arahant and after Parinibbana. He should at least attempt to be a Sotapanna, which will free him from rebirth in a woeful state.

Good householder,

Once one stopps unskillful kamma, old runs out and no new is performed. That's the way practice is leading to an aim, an end. No need to think much on past anymore, one firm resolve, after seeing the backwards, is done.

Sure things may have possibilities to rippen but woundn't be that hard to bear.

Good if reading the story of the mass-killer Angolimala and his way to Arahat-hood.

Angulimala: A Murderer's Road to Sainthood

"Abandon what is unskillful. It is possible to abandon what is unskillful. If it were not possible to abandon what is unskillful, I would not say to you, 'Abandon what is unskillful.' But because it is possible to abandon what is unskillful, I say to you, 'Abandon what is unskillful.' If this abandoning of what is unskillful were conducive to harm and pain, I would not say to you, 'Abandon what is unskillful.' But because this abandoning of what is unskillful is conducive to benefit and pleasure, I say to you, 'Abandon what is unskillful.'

May all soon go after right effort and stopp soon, for the happiness of themselves and many.

[Note that this gift isn't given for stacks, exchange, or other world-binding trades, but for release from this wheel]

Please see this question, this answer and this answer for details.

To summarize (from the perspective of the Five Precepts and Right Livelihood for lay people):

• It's ok to grow, harvest and consume vegetables and fruits (without the use of pesticides), because they are not sentient
• It is wrong to kill or directly cause the killing of animals
• It is wrong to have a livelihood on the business of meat and sentient beings
• It is wrong to consume meat that is from an animal that is seen, heard or suspected to have been slaughtered specifically for you
• It is ok to purchase and consume meat from the market (that was already dead long before you arrived at the market)
• It is ok to order a meal from a restaurant, which is based on frozen meat

So for a customer who goes to a seafood restaurant - if he has to choose a living lobster, from an aquarium, to be cooked for him, then this breaks the first precept.

However, if the customer picks his meal from a menu, which is cooked from a frozen dead lobster which comes out of the freezer, then this does not break the first precept.

For the chef and owner of the seafood restaurant however, this breaks Right Livelihood, because it is a business of meat (maṃsavaṇijjā). Please see AN 5.177.

In addition, if lobsters are purchased and put into an aquarium for this seafood restaurant business, that's the business made upon sentient beings (sattavaṇijjā) from the same sutta. This also breaks Right Livelihood. Human trafficking (e.g. forced prostitution, slave labour) and a circus with animals are also considered businesses made upon sentient beings.

He is also doing very well in the 5 basic lay Buddhist precepts and has changed entirely the mindset and behavior after studying Buddhism.

That's pretty much the key point here. While there's no surefire way to know exactly how Kamma will unfold unless one's already attained enlightenment, by cultivating the Path, there's always hope that things will turn out ok at the end:

"Monks, for anyone who says, 'In whatever way a person makes kamma, that is how it is experienced,' there is no living of the holy life, there is no opportunity for the right ending of stress. But for anyone who says, 'When a person makes kamma to be felt in such & such a way, that is how its result is experienced,' there is the living of the holy life, there is the opportunity for the right ending of stress.

"There is the case where a trifling evil deed done by a certain individual takes him to hell. There is the case where the very same sort of trifling deed done by another individual is experienced in the here & now, and for the most part barely appears for a moment. ~~ AN 3.99 ~~