Omega from Fish:
Dogs and cats need both omega 3 and omega 6 fatty acids for optimal health. Fish is high in protein and is an excellent source of fatty acids, vitamins and minerals. Fatty acids from fish is beneficial for cats & dogs young & old.
Omega 3 from plant sources: Plant sources ( Flaxseed included) of omega 3 (LNA) are extremely inefficient means for your pet to receive the essential fatty acids that they need. 10 grams of LNA are required to convert to just 1 gram of EPA. This conversion can be difficult or impossible for some older animals.