There's a someone that makes Herring at Pomegranate supermarket in Boro Park under Pomegranate's name.
He confirmed to me that the following 2 are clean and made with canola oil and salt only (and pepper for the Pepper Crusted)
Shmaltz Pepper Crusted Herring
(the ingredients list might say sugar but it is because he can't say that the the kitchen is sugar-free since he's also doing other herring, so it's easier to write sugar...)
I hope that helps...
All the best