Many horse owners think that supplementing their horses’ diets with fish oil is beneficial. In reality, you are supplementing with the incorrect Omega-3. Fish oils are high in two Omega-3 fatty acids: DHA and EPA. It is not recommended to feed horses fish oil. Fish oil is not a natural form of Omega-3 fatty acid that a horse would consume in the wild. They may still be Omega-3 deficient if you are supplementing with fish oil; as you are not providing them enough ALA.