>this food also uses added Methionine<
Jo you're not getting methionine confused with menadione? Methionine is an essential amino acid :)
If indeed the 'protein' word is a pretty word for derivatives than this food is not much better than most of the others :( Hoooooweveeeer,i would rather see a pet owner feed a food like wainwrights rather than pedigree,bakers,beta et al which have by-products,derivatives,colours, grains,grain,grains and around 2-4% meat

Compared to foods such as these this one is a huge step up.
I forgot to add that wainwrights is - 30% protein and 15% fat.
Here are the ingredients and GA for JWB fish-
Ingredients: Rice, Ocean White Fish Meal, Barley, Whole Linseed, Olive Oil, Vegetable Gravy, Peas, Fish Oil, Alfalfa, Natural Seaweed, Chicory Pulp, Sodium Chloride, Calcium Carbonate, D,L-methionine, Lysine Hydrochloride, Threonine, Zinc Methionate.>Contains: Min. 23% Fish, Min 28% Rice, Min 15% Barley<
>Typical Analysis: Protein 21%, Oil 10%, Fibre 4%, Ash 8%.<
The fat and protein in wainwrights is at a much more appropriate level for maintenance,but the question is how and where is the protein being provided. You would have to find out the digestability of the foods to know exactly the amounts and how much of the protein and fat the dog can actually absorb/digest. A food can have 40% protein with ingredients of a leather belt and a pair of leather shoes,but none of it would be available to the dog.