How much Omega-6 does sprat have?
Fish contain very little n-6 (Omega-6 aka linoleic) fatty acids by nature. Most of the n-6 fats are contributed by vegetable sources during processing, such as vegetable oils used in coatings or pre-cooking. The amount of n-6 fats will depend on how the fish is processed and in which oil.

The US National Library of Medicine has a brief article at this page. Info on n-3 and n-9 fatty acids in sprats can be found here