Soak fish in milk 10 minutes. Remove, sprinkle with salt and coat with flour.
Heat 2 tablespoons oil in a frying pan over medium-high heat. Cook fish until it is golden on one side, about 3 minutes. Cook second side until golden and cooked through, about 3 to 4 more minutes. Remove fish to a serving platter.
Wipe frying pan clean. Reduce heat to low, add remaining oil and cook garlic 30 seconds. Add lime juice, lemon juice, orange juice, parsley and spring onions. Add butter, swirl in frypan until just creamy. Pour sauce over fish and serve.