ive only just come across this question...but its still relevant to...I'm doing a 1st year catering course found the following inforamtion "...Firm, white, mild fish that can be cut into thick fillets are the best substitutes for monkfish. Angel fish most closely resembles monkfish although they are not related. Angel fish is comparable in weight and yield and can be prepared using the same cooking methods as monkfish. Grouper, red snapper, black cod (sablefish), striped bass, tilefish, turbot, orange roughy, Alaskan Pollock, sturgeon, hake (whiting) can also replace monkfish in a variety of recipes. These types of fish fare well with the same cooking techniques used for monkfish..."