Preheat the oven to 375º F and line a baking sheet with parchment paper. (Parchment is optional, but leaves you with much less clean up!)
Distribute the tortilla chips over the baking sheet in an even layer.
Sprinkle most, if not all, of the cheese evenly over the chips. (You can save some cheese to sprinkle on top of all the toppings at the end, if you wish.)
Stir the diced bell pepper, red onion, and tomatoes together in a large bowl to mix them up nicely, then evenly distribute the combination over the chips; do the same with the sliced black olives.
Dump all of the drained mackerel into a bowl along with the jalapeño peppers it was packed with. With a fork, mash the mackerel into large flakes. Sprinkle the large flakes of mackerel evenly over the dressed up chips.
Place in the oven and bake for about 10-15 minutes, or until all of the cheese has melted.
Garnish with chopped fresh parsley or cilantro.
Serve hot/warm, along with pico de gallo, sour cream or plain Greek yogurt, and fresh lime wedges.