Rinse guajillo and chipotle chiles. Heat a large skillet (with a lid) over medium-high heat, add chiles, and cook, turning, until fragrant, about 40 seconds. Transfer chiles to a bowl, cover with hot water, and soak until soft, about 25 minutes. Drain chiles and remove and discard stems and seeds. (It is best to wear rubber gloves when handling chiles because oils can irritate skin.)
Place chiles in a blender. Gradually add fish stock and purée until smooth. Press through a sieve into a small bowl.
Heat oil in same skillet over high heat. Add shrimp and cook, turning once, until pink and firm, about 1 minute. Season with salt and pepper. Remove from skillet.
Reduce heat to medium, add garlic to skillet, and cook, stirring, until fragrant, 1-2 minutes. Carefully stir in chile purée (it tends to spatter). Reduce heat to medium-low, cover, and simmer, stirring occasionally, until flavors blend, 10 minutes.
Just before serving, add mayonnaise to chile mixture, whisk until well blended, then add shrimp. Cook uncovered until heated through, about 2 minutes. (Take care not to overcook the sauce, or the mayonnaise will curdle.) Adjust seasoning with salt and pepper. Garnish with lime and serve warm with corn tortillas or rice if desired.