Steve,
Back in brexit blighted - oops, sorry, brexit Blighty - food price inflation last month reached 4.2% compared with 0.6% this time last year.

Overall inflation has peaked and is now expected to decline.
Food inflation is caused by our having to import expensive food from EU, or from elsewhere with tariffs adding to the cost.
All that will change with brexit.
You single out fish, which will be much cheaper when we stop EU boats plundering our fish stocks.