言うまでもなく - Needless to say, it goes without saying
鮮魚わ - As for fresh fish (I assume this is supposed to be the topic-marking particle)
鮮度が - The level of freshness
命です - Is life (I'm almost positive I've seen this used to mean extremely important)
So my best translation would be: 'It goes without saying that when it comes to fresh fish, the level of freshness is of paramount importance'. If I'm wrong about 命, then I'm a bit lost as well though