Note 2 - Significant Accounting Policies - Revenue By Product (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Revenue	$ 10,044	$ 9,150	$ 24,143	$ 26,014
Packaged Astaxanthin [Member]
Revenue	6,012	5,746	15,388	15,649
Packaged Spirulina [Member]
Revenue	3,212	2,268	6,208	6,560
Packaged Products [Member]
Revenue	9,224	8,014	21,596	22,209
Bulk Astaxanthin [Member]
Revenue	287	317	884	748
Bulk Spirulina [Member]
Revenue	533	819	1,663	3,057
Bulk Products [Member]
Revenue	820	1,136	2,547	3,805
Astaxanthin [Member]
Revenue	6,299	6,063	16,272	16,397
Spirulina [Member]
Revenue	$ 3,745	$ 3,087	$ 7,871	$ 9,617

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.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130543-203045

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130539-203045

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130545-203045

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