You can choose either the Crispy Fish or Cajun Fish sandwich.
The Crispy Fish features a crispy-fried, wild-caught Alaskan Pollock filet served with tartar sauce, and shredded lettuce on a toasted sesame seed bun, while the Cajun Fish includes the same but swaps out the tartar sauce for Cajun Spread.
You can expect the deal to stick around at least through Easter (April 21, 2019) at participating locations.
Photo via Arby's.