Using a food processor, finely grind almonds. Combine in a shallow dish with bread crumbs, garlic salt, and paprika.
In a separate shallow dish, whisk egg and buttermilk.
Over medium heat, melt butter in a frying pan large enough to hold fish fillets without crowding (use two pans if necessary). When butter is nicely browned (about 8 minutes), add olive oil.
Pat dry fish fillets. Roll thoroughly in egg-milk mixture, then dredge in bread-crumb mixture. Add to hot pan. Cook, without disturbing, until browned (about 6 minutes), then flip and cook other side until just opaque. Serve with a squeeze of fresh lemon.