Zest the blood oranges into a shallow bowl and set aside. Segment the grapefruit and all of the oranges by cutting away the peel and white pith with a sharp knife, leaving the flesh exposed, then carefully cut between the membranes to release each segment into a medium bowl. Reserve the membranes from the oranges and set the shallow bowl aside.
Add the jalapeno, the scallion whites, cilantro, endive, and lime juice to the medium bowl. Season with a pinch or two of salt and stir to combine. Refrigerate the citrus salsa until ready to serve.
Add the mustard to the shallow bowl. Squeeze in the juice from the reserved blood orange membranes and whisk to combine. If the mixture seems too thick, squeeze in more juice from the remaining orange membranes.
Combine the pistachios with the panko and a couple of pinches of salt in a food processor and process until the pistachios are finely chopped and well combined with the panko. Transfer to another shallow bowl.
Pat the fish fillets dry then season with salt and pepper. Heat the oil in a large nonstick skillet over medium-high heat.
Meanwhile, dip each fillet in the citrus-Dijon mixture then dredge in the pistachio breadcrumbs, pressing to help the crumbs adhere, if necessary. Add the fillets to the skillet and cook until the nuts are golden brown and the fish is opaque and flakes easily with a fork, 3 to 4 minutes per side.
Remove the fillets to serving plates, garnish with the remaining scallion greens and spoon some of the citrus salsa on the side or over the top with a slotted spoon.