Fish oil is one of those supplements that looks simple until you flip the bottle around. Two products can both say omega-3, but one gives you a useful dose of EPA and DHA and the other is mostly branding.
A few things worth checking:
First, the actual EPA + DHA amount. A lot of bottles brag about 1,000 mg of fish oil, but the meaningful number is the combined EPA and DHA. The N1 research stack puts the common evidence-based range around 1 to 2 grams per day for most people.
Second, the form. Triglyceride-form fish oil tends to absorb better than ethyl ester. Not every label makes this obvious, which is annoying, but it matters.
Third, freshness and testing. Third-party testing for heavy metals matters, IFOS certification is a good sign, and a strong fishy smell is usually a bad one. Fresh oil should not smell like you regret opening it.
And if you do not eat much fatty fish, algae oil is a legit option too. Same goal: get enough EPA and DHA without guessing.
Not medical advice, especially if you take blood thinners. But I am curious: what is your personal filter for omega-3 supplements before you buy one?