Actually because of you I just researched one brand and bought it, so jazakAllah. Brand is NoorVitamins, I mean they seem legit, reviews confirming their halal status..... I can let you know what I think of them when they come. Here is a link
https://www.amazon.com/dp/B005E9JXHS...sp_detail_page
The brand I was previously using, Nordic Naturals, was very high quality and had beef gelatin, but I'm sure it wasn't halal slaughtered beef, never thought to look for halal omega 3 or vitamins at all, but I think I have a good basis for comparison since the one I was using is of high quality.