Seafood - End and The Alternative Karma Consequences

Assume a scenario that a seafood chef that inherited from the parent's seafood restaurant business and used to kill seafood alive before have a chance to study Buddhism. When the chef understood the basic and respect the basic perspective of Buddhism then he tried hard and changed his job/business entirely to a job that not required to kill animal/seafood alive. He is also doing very well in the 5 basic lay Buddhist precepts and has changed entirely the mindset and behavior after studying Buddhism. What would happen to animal/seafood that had been killed before? Does he still need go thru the Karma consequences or a least some waiver of punishment or this person is still going to hell but a better hell or how to reduce the bad karma consequences further? https://en.wikipedia.org/wiki/Five_precepts This question is similar to the below but couldn't find the answer https://buddhism.stackexchange.com/questions/22433/what-does-ending-karma-mean Post Note: This question is more specific to the Chef and Seafood karma issue. The bad karma should go to those folks that order the Chef to kill and to consume the fresh and taste of seafood. At least to those folks that basic Buddhism theory/common sense already exposed to them. Correct me from wrong if any. Lobster is best tasted when boiled alive and also it is also known to have the highest consciousness level in term of vision of all being on earth https://science.howstuffworks.com/lobster-x-ray-technology.htm