Eating fish on a Friday used to be common practice in Ireland, and it's a tradition worth reviving. Fish offer a useful source of protein, and if you opt for oily fish like salmon and mackerel they can also provide decent amounts omega-3 fatty acids.
You may have heard about these fatty acids - which are called omega-3 due to their chemical structure - being linked with health benefits. While the jury is out on whether they can reduce the risk of some medical conditions, there does seem to be evidence that eating omega-3 fats can help your heart. You can read more about omega-3 fatty acids and health on the NHS and University of Maryland websites.