Farm-raised salmon are naturally grey while wild salmon are naturally pink due to their diet which includes astaxanthin, a compound found in krill and shrimp. Salmon farmers have to add astaxanthin to their feed to give them the pink color. It is the most expensive part of their food. – WTF Fun Facts
salmon
salmon have an incredibly good sense of smell
Salmon have an incredibly good sense of smell which they use to return to the same stream to spawn. It is 1000x better than a dog’s sense of smell.