Rinse and pat dry white fish with paper towels. Place skin side down on lined baking tray. Drizzle lemon juice over the top then sprinkle with salt and pepper.
Combine basil, garlic, pistachios, parmesan cheese, and salt in a food processor. Give it a few pulses. With machine running, gradually add olive oil through the feed tube of food processor. Process until smooth.
Divide pistachio pesto into 4 portions. Spread each portion evenly onto each slab of white fish.
Sprinkle finely crushed rice Krispies on the top to form a crust.