I dont know if dream recall and normal memory function are related in the way you suggest . There seem to be other factors involved in dream recall . I read that the brain has a specific mechanism for deleting dreams on wakening and that the fact that we remember dreams at all is rather by chance such as awakening at the wrong moment in the sleep cycle or just by training ourselves to override the 'delete mechanism'
I think you may have an effect from eating oily fish before sleeping because it is not easily digested and will affect your sleep pattern . Interestingly there was recent research in the UK about the effect of eating cheese on dreams . The best result came from people who ate Stilton , they reported a measurable increase in dream imagery and vividness . I dont know if this is to do with the high fat content of Stilton or is it a specific effect of the mould in blue cheeses or maybe some chemical in the mould culture .