It was well known that eating lots of fish was really good for your brain and that it would make you and your children smarter. Fish oil supplements, omega threes and all sorts become hot sellers and everyone ate lots of fish and capsules. Then we were told it wasn't true, then it was true, then it wasn't true. The fashion for fish soon passed.
Well, here's the thing, there are indeed elements in food that are vital for effective brain development and functioning. Eating a ton of fish may not turn your child in Einstein, but depriving your child or yourself of these important nutrients may well render your brain less than functional.
Don't believe the hype, but do eat fish, or things rich in omega 3.
You don't need to cover the fish in batter and deep fry it and serve it with potato chips/fries either. That would be silly.
B vitamins are also really important for brain function - whole grains, fish, lentils/pulses are important sources for these vitamins. Brain foods play an important role in the prevention of brain diseases such as dementia. High processed foods, tinned things, packet foods, and refined food score very low on essential nutrients and are best avoided as part of a healthy diet. Go fresh, go wholegrain, go fish!