The Louisville-based chain will offer "all you can eat" fried fish, chicken and sides with prices starting at $7.99 from Feb. 17-25, it said in a press release.
Then, for Lent, which is from Feb. 26 to April 9 this year, Long John Silver's will offer a "two for $6" menu with items like shrimp, crab cakes, Alaska Pollock and chicken tenders, as well as larger $10 "Sea-Share" dishes.
The chain will also offer the "all you can eat" menu on Sundays during Lent. On Mondays, customers can bring in coupons from other restaurants to pay $1.99 for an Alaska Pollock sandwich or fish and fries.
The Christian holiday provides a major sales boost for Long John Silver's. The chain sells about 20 million pieces of fish during Lent and 450,000 shrimp on Ash Wednesday alone, SeafoodSource reported in 2016.
Lent has been a factor in fast-food sales since the industry's early days. A McDonald's franchisee in Catholic-heavy Cincinnati famously invented the Filet-O-Fish sandwich in the early 1960s after noticing a drop in sales during the holiday. Today, the fish sandwich still helps "drive sales and guest counts," McDonald's executive vice president and CFO Kevin Ozan told investors last year.