Im looking for an old shmup...

[BulletMagnet]

I do remember the big fish clearly though, and I think it turned backwards during its swimming cycle.

That sounds more like Darius Gaiden, though that boss was yellow.

[Obiwanshinobi]

Metal Black sports mechanical fish swimming as the scoreboard's background. They are turning backwards indeed.

[kamiboy]

Metal Black sports mechanical fish swimming as the scoreboard's background. They are turning backwards indeed.

What a great thing this youtube is that I can go into it, type in the name of any obscure game and watch an entire playthrough of it. That being said, no dice, this is not the game. But I liked the art direction of this game, so it was not wasted time watching that video.

[kamiboy]

I do remember the big fish clearly though, and I think it turned backwards during its swimming cycle.

That sounds more like Darius Gaiden, though that boss was yellow.

Ugh, no, Darius Gaiden is one of those games that uses rendered sprites. Definitely not this one, unless my memory deceived me the game I am looking for had beautiful pixel graphics.