Norwegian fish oil supplements such as NORSK TRAN or Icelandic from LISI H.F. - undoubtedly of high quality, but sometimes not justifiably expensive.
From Western manufacturers, it is much more profitable and effective in many cases to use drugs from American manufacturers Solgar, Natrol, Now: they all undergo the necessary certification and have excellent reviews among consumers.
Among Russian brands it is worth highlighting CMTech, GeneticLab Nutrition or Be First. These brands offer quality products and are sold at prices significantly different from those of Norwegian products.
A large selection of drugs similar to Norwegian are offered in addition to pharmacies by sports food stores, for example, you can see here.
Norwegian fish oil is one of the highest quality and, unfortunately, there is no adequate domestic substitute.
If you want quality fish oil, but not very expensive, choose cod liver oil. It has a good composition and is inexpensive