Note 13 - Segment Reporting, Product Line and Geographic Information - Net Sales by Product Line (Details) - USD ($) $ in Thousands	12 Months Ended
Mar. 31, 2025	Mar. 31, 2024
Total net sales	$ 24,215	$ 23,071
Packaged Astaxanthin [Member]
Total net sales	13,145	13,613
Packaged Spirulina [Member]
Total net sales	5,223	5,779
Packaged Products [Member]
Total net sales	18,368	19,392
Bulk Astaxanthin [Member]
Total net sales	2,593	1,491
Bulk Spirulina [Member]
Total net sales	2,405	1,572
Bulk Products [Member]
Total net sales	4,998	3,063
Contract Extraction and R&D Services [Member]
Total net sales	$ 849	$ 616

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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+ Details