Who makes Kirkland Signature Fish Oil 1000 mg., 400 Softgels?
As of September 28, 2026, evidence points to Pharmavite as the manufacturer of Kirkland Signature Fish Oil 1000 mg., 400 Softgels, but no tier 1–3 source names the link directly.
The common claim
What’s commonly claimed, and what the evidence supports
The dominant online answer, spread by content sites since a 2018 mislabeling lawsuit, says Trident Seafoods for all Kirkland fish oil. The verifiable part covers only the Wild Alaskan 1400 mg variant: the 2018 federal complaint and the Seattle Times named Trident Seafoods as that product's manufacturer, and Costco's own listing data for it carries TRIDENT SEAFOOD CORP. For the flagship USP-verified Fish Oil 1000 mg, Costco's product-listing data instead points to Pharmavite, the company behind Nature Made. Older claims crediting Nature's Bounty (NBTY) circulate with no verifiable support: full-text search of NBTY's SEC filings (2001 onward) finds no Kirkland Signature mention.
Evidence & sources
Each source is graded on the six-tier evidence rubric, where tier 1 is strongest. Sources are archived, so a citation still works if the original page moves or goes behind a paywall.
Tier 4
Costco's own page embeds catalog JSON whose manufacturer field names Pharmavite for this exact product: an item record with parentId 11072245 (this product), UPC 096619112531, shortDescription 'Kirkland Signature Omega-3 Fish Oil Concentrate 1000 mg, 400 Softgels', features '1000 mg \"Concentrated\" Fish Oil with 300 mg Omega-3 Fatty Acids', item startDate 2009-03-16, carries 'PHARMAVITE' in Costco's manufacturer field. The same value appears in the 2026-01-18 snapshot of the page. Graded probable rather than confirmed because it is an internal catalog field, not an editorial statement: the product's newer sibling item record masks the field with the brand name ('Kirkland Signature(TM)'), and the field could reflect the vendor of record rather than the plant, though for a private-label supplement those are normally the same company. Pharmavite is the maker of Nature Made.
Tier 4
Variant clarification carrying the common-claim debunk: on the Wild Alaskan 1400 mg page, both embedded item records (startDates 2014-12-23 and 2015-11-17) carry 'TRIDENT SEAFOOD CORP' / 'TRIDENT SEAFOODS CORP' in Costco's manufacturer field, and costco.com's fish-oil category exposes a matching 'manufacturername=trident-seafood-corp' filter. Trident is documented for this variant only, not for the flagship 1000 mg softgels this record covers, whose field names Pharmavite.
Tier 4
Names Trident for the Wild Alaskan variant (the source most 'Trident makes Kirkland fish oil' answers trace back to): 'Lawyers for a New York man who bought Costco's Kirkland Signature Wild Alaskan Fish Oil sued the company and manufacturer Trident Seafoods this week', and notes the supplement is one Trident 'also manufacturers for Costco competitors Sam's Club and BJ's.' The suit is Leibowitz v. Costco Wholesale Corp., E.D.N.Y. 2:18-cv-01254 (filed 2018-02-27, CourtListener docket 6713929); SeafoodSource reported it ended in voluntary dismissal. Included to scope the Trident claim to the 1400 mg variant.
Frequently asked
Who makes Kirkland Signature fish oil?
Is Kirkland fish oil made by Trident Seafoods?
Is Kirkland Signature fish oil USP verified?
Is Kirkland fish oil the same as Nature's Bounty?
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