Dice the tomato, onion, serrano pepper, cilantro and Catfish.
Combine in a bowl and mix well.
Add minced garlic and salt.
Squeeze lime juice over mixture until covered.
Cover and refrigerate for at least 8 hours, stirring 2 to 3 times. The acid in the lime juice will cook the fish.
Serve with your favorite tortilla chips or on a tostada.
*Always use the freshest fish possible and make the ceviche the same day you purchase the fish. Store your fish in the refrigerator on ice, before making ceviche.