<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.25.0.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>185</ContextCount>
  <ElementCount>258</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>51</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>7</UnitCount>
  <MyReports>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>000 - Document - Document And Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-document-and-entity-information</Role>
      <ShortName>Document And Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>001 - Statement - Condensed Consolidated Balance Sheets (Current Period Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-condensed-consolidated-balance-sheets-current-period-unaudited</Role>
      <ShortName>Condensed Consolidated Balance Sheets (Current Period Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>002 - Statement - Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-condensed-consolidated-balance-sheets-current-period-unaudited-parentheticals</Role>
      <ShortName>Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>003 - Statement - Condensed Consolidated Statements of Operations (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-condensed-consolidated-statements-of-operations-unaudited</Role>
      <ShortName>Condensed Consolidated Statements of Operations (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>004 - Statement - Condensed Consolidated Statements of Stockholders' Equity (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-condensed-consolidated-statements-of-stockholders-equity-unaudited</Role>
      <ShortName>Condensed Consolidated Statements of Stockholders' Equity (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>005 - Statement - Condensed Consolidated Statements of Cash Flows (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-condensed-consolidated-statements-of-cash-flows-unaudited</Role>
      <ShortName>Condensed Consolidated Statements of Cash Flows (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>006 - Disclosure - Note 1 - Organization and Basis of Presentation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-1-organization-and-basis-of-presentation</Role>
      <ShortName>Note 1 - Organization and Basis of Presentation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>007 - Disclosure - Note 2 - Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-2-significant-accounting-policies</Role>
      <ShortName>Note 2 - Significant Accounting Policies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>008 - Disclosure - Note 3 - Inventories</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-3-inventories</Role>
      <ShortName>Note 3 - Inventories</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>009 - Disclosure - Note 4 - Equipment and Leasehold Improvements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-4-equipment-and-leasehold-improvements</Role>
      <ShortName>Note 4 - Equipment and Leasehold Improvements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>010 - Disclosure - Note 5 - Line of Credit and Long-term Debt</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-5-line-of-credit-and-longterm-debt</Role>
      <ShortName>Note 5 - Line of Credit and Long-term Debt</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>011 - Disclosure - Note 6 - Operating Leases</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-6-operating-leases</Role>
      <ShortName>Note 6 - Operating Leases</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>012 - Disclosure - Note 7 - Accrued Expenses</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-7-accrued-expenses</Role>
      <ShortName>Note 7 - Accrued Expenses</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>013 - Disclosure - Note 8 - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-8-commitments-and-contingencies</Role>
      <ShortName>Note 8 - Commitments and Contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>014 - Disclosure - Note 9 - Share-based Compensation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-9-sharebased-compensation</Role>
      <ShortName>Note 9 - Share-based Compensation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>015 - Disclosure - Note 10 - Stockholders' Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-10-stockholders-equity</Role>
      <ShortName>Note 10 - Stockholders' Equity</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>016 - Disclosure - Note 11 - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-11-income-taxes</Role>
      <ShortName>Note 11 - Income Taxes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>017 - Disclosure - Note 12 - Earnings Per Share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-12-earnings-per-share</Role>
      <ShortName>Note 12 - Earnings Per Share</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>018 - Disclosure - Note 13 - Related Party Transactions</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-13-related-party-transactions</Role>
      <ShortName>Note 13 - Related Party Transactions</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>019 - Disclosure - Note 14 - Subsequent Events</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-14-subsequent-events</Role>
      <ShortName>Note 14 - Subsequent Events</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>995445 - Disclosure - Insider Trading Arrangements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/ecd/role/InsiderTradingArrangements</Role>
      <ShortName>Insider Trading Arrangements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>995466 - Disclosure - Significant Accounting Policies (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-significant-accounting-policies-policies</Role>
      <ShortName>Significant Accounting Policies (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <ParentRole>http://www.cyanotech.com/20241231/role/statement-note-2-significant-accounting-policies</ParentRole>
      <Position>22</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>995467 - Disclosure - Note 2 - Significant Accounting Policies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-2-significant-accounting-policies-tables</Role>
      <ShortName>Note 2 - Significant Accounting Policies (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cyanotech.com/20241231/role/statement-note-2-significant-accounting-policies</ParentRole>
      <Position>23</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>995468 - Disclosure - Note 3 - Inventories (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-3-inventories-tables</Role>
      <ShortName>Note 3 - Inventories (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cyanotech.com/20241231/role/statement-note-3-inventories</ParentRole>
      <Position>24</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>995469 - Disclosure - Note 4 - Equipment and Leasehold Improvements (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-4-equipment-and-leasehold-improvements-tables</Role>
      <ShortName>Note 4 - Equipment and Leasehold Improvements (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cyanotech.com/20241231/role/statement-note-4-equipment-and-leasehold-improvements</ParentRole>
      <Position>25</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>995470 - Disclosure - Note 5 - Line of Credit and Long-term Debt (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-5-line-of-credit-and-longterm-debt-tables</Role>
      <ShortName>Note 5 - Line of Credit and Long-term Debt (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cyanotech.com/20241231/role/statement-note-5-line-of-credit-and-longterm-debt</ParentRole>
      <Position>26</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>995471 - Disclosure - Note 6 - Operating Leases (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-6-operating-leases-tables</Role>
      <ShortName>Note 6 - Operating Leases (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cyanotech.com/20241231/role/statement-note-6-operating-leases</ParentRole>
      <Position>27</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>995472 - Disclosure - Note 7 - Accrued Expenses (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-7-accrued-expenses-tables</Role>
      <ShortName>Note 7 - Accrued Expenses (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cyanotech.com/20241231/role/statement-note-7-accrued-expenses</ParentRole>
      <Position>28</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>995473 - Disclosure - Note 9 - Share-based Compensation (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-9-sharebased-compensation-tables</Role>
      <ShortName>Note 9 - Share-based Compensation (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cyanotech.com/20241231/role/statement-note-9-sharebased-compensation</ParentRole>
      <Position>29</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>995474 - Disclosure - Note 12 - Earnings Per Share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-12-earnings-per-share-tables</Role>
      <ShortName>Note 12 - Earnings Per Share (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.cyanotech.com/20241231/role/statement-note-12-earnings-per-share</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>995475 - Disclosure - Note 1 - Organization and Basis of Presentation (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-1-organization-and-basis-of-presentation-details-textual</Role>
      <ShortName>Note 1 - Organization and Basis of Presentation (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cyanotech.com/20241231/role/statement-note-1-organization-and-basis-of-presentation</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>995476 - Disclosure - Note 2 - Significant Accounting Policies (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-2-significant-accounting-policies-details-textual</Role>
      <ShortName>Note 2 - Significant Accounting Policies (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cyanotech.com/20241231/role/statement-note-2-significant-accounting-policies-tables</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>995477 - Disclosure - Note 2 - Significant Accounting Policies - Revenue By Product (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-2-significant-accounting-policies-revenue-by-product-details</Role>
      <ShortName>Note 2 - Significant Accounting Policies - Revenue By Product (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>33</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>995478 - Disclosure - Note 3 - Inventories (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-3-inventories-details-textual</Role>
      <ShortName>Note 3 - Inventories (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cyanotech.com/20241231/role/statement-note-3-inventories-tables</ParentRole>
      <Position>34</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>995479 - Disclosure - Note 3 - Inventories - Components of Inventory (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-3-inventories-components-of-inventory-details</Role>
      <ShortName>Note 3 - Inventories - Components of Inventory (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>995480 - Disclosure - Note 4 - Equipment and Leasehold Improvements (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-4-equipment-and-leasehold-improvements-details-textual</Role>
      <ShortName>Note 4 - Equipment and Leasehold Improvements (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cyanotech.com/20241231/role/statement-note-4-equipment-and-leasehold-improvements-tables</ParentRole>
      <Position>36</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>995481 - Disclosure - Note 4 - Equipment and Leasehold Improvements - Components of Equipment and Leasehold Improvements (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-4-equipment-and-leasehold-improvements-components-of-equipment-and-leasehold-improvements-details</Role>
      <ShortName>Note 4 - Equipment and Leasehold Improvements - Components of Equipment and Leasehold Improvements (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>995482 - Disclosure - Note 5 - Line of Credit and Long-term Debt (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-5-line-of-credit-and-longterm-debt-details-textual</Role>
      <ShortName>Note 5 - Line of Credit and Long-term Debt (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cyanotech.com/20241231/role/statement-note-5-line-of-credit-and-longterm-debt-tables</ParentRole>
      <Position>38</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>995483 - Disclosure - Note 5 - Line of Credit and Long-term Debt - Summary of Line of Credit and Long-term Debt (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-5-line-of-credit-and-longterm-debt-summary-of-line-of-credit-and-longterm-debt-details</Role>
      <ShortName>Note 5 - Line of Credit and Long-term Debt - Summary of Line of Credit and Long-term Debt (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>39</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>995484 - Disclosure - Note 5 - Line of Credit and Long-term Debt - Future Payments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-5-line-of-credit-and-longterm-debt-future-payments-details</Role>
      <ShortName>Note 5 - Line of Credit and Long-term Debt - Future Payments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>995485 - Disclosure - Note 6 - Operating Leases (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-6-operating-leases-details-textual</Role>
      <ShortName>Note 6 - Operating Leases (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cyanotech.com/20241231/role/statement-note-6-operating-leases-tables</ParentRole>
      <Position>41</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>995486 - Disclosure - Note 6 - Operating Leases - Supplemental Balance Sheet Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-6-operating-leases-supplemental-balance-sheet-information-details</Role>
      <ShortName>Note 6 - Operating Leases - Supplemental Balance Sheet Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>995487 - Disclosure - Note 6 - Operating Leases - Operating Leases Maturities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-6-operating-leases-operating-leases-maturities-details</Role>
      <ShortName>Note 6 - Operating Leases - Operating Leases Maturities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>43</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>995488 - Disclosure - Note 7 - Accrued Expenses - Components of Accrued Expenses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-7-accrued-expenses-components-of-accrued-expenses-details</Role>
      <ShortName>Note 7 - Accrued Expenses - Components of Accrued Expenses (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>995489 - Disclosure - Note 9 - Share-based Compensation (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-9-sharebased-compensation-details-textual</Role>
      <ShortName>Note 9 - Share-based Compensation (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cyanotech.com/20241231/role/statement-note-9-sharebased-compensation-tables</ParentRole>
      <Position>45</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>995490 - Disclosure - Note 9 - Share-based Compensation - Shares Authorized, Available for Future Grant and Outstanding Under Each Plan (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-9-sharebased-compensation-shares-authorized-available-for-future-grant-and-outstanding-under-each-plan-details</Role>
      <ShortName>Note 9 - Share-based Compensation - Shares Authorized, Available for Future Grant and Outstanding Under Each Plan (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>995491 - Disclosure - Note 9 - Share-based Compensation - Summary of Option Activity Under Stock Plans (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-9-sharebased-compensation-summary-of-option-activity-under-stock-plans-details</Role>
      <ShortName>Note 9 - Share-based Compensation - Summary of Option Activity Under Stock Plans (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>995492 - Disclosure - Note 9 - Share-based Compensation - Summary of Non-vested Options (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-9-sharebased-compensation-summary-of-nonvested-options-details</Role>
      <ShortName>Note 9 - Share-based Compensation - Summary of Non-vested Options (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>48</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>995493 - Disclosure - Note 9 - Share-based Compensation - Restricted Stock Units (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-9-sharebased-compensation-restricted-stock-units-details</Role>
      <ShortName>Note 9 - Share-based Compensation - Restricted Stock Units (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>995494 - Disclosure - Note 10 - Stockholders' Equity (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-10-stockholders-equity-details-textual</Role>
      <ShortName>Note 10 - Stockholders' Equity (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cyanotech.com/20241231/role/statement-note-10-stockholders-equity</ParentRole>
      <Position>50</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>995495 - Disclosure - Note 11 - Income Taxes (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-11-income-taxes-details-textual</Role>
      <ShortName>Note 11 - Income Taxes (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cyanotech.com/20241231/role/statement-note-11-income-taxes</ParentRole>
      <Position>51</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>995496 - Disclosure - Note 12 - Earnings Per Share - Summary of Reconciliations Between the Numerator and the Denominator of the Basic and Diluted Earnings Per Share Computations (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-12-earnings-per-share-summary-of-reconciliations-between-the-numerator-and-the-denominator-of-the-basic-and-diluted-earnings-per-share-computations-details</Role>
      <ShortName>Note 12 - Earnings Per Share - Summary of Reconciliations Between the Numerator and the Denominator of the Basic and Diluted Earnings Per Share Computations (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>52</Position>
    </Report>
    <Report instance="cyan20241231_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>995497 - Disclosure - Note 13 - Related Party Transactions (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.cyanotech.com/20241231/role/statement-note-13-related-party-transactions-details-textual</Role>
      <ShortName>Note 13 - Related Party Transactions (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.cyanotech.com/20241231/role/statement-note-13-related-party-transactions</ParentRole>
      <Position>53</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File>cyan-20241231.xsd</File>
    <File>cyan-20241231_cal.xml</File>
    <File>cyan-20241231_def.xml</File>
    <File>cyan-20241231_lab.xml</File>
    <File>cyan-20241231_pre.xml</File>
    <File doctype="10-Q" isDefinitelyFs="true" isUsgaap="true" original="cyan20241231_10q.htm">cyan20241231_10q.htm</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy items="606">http://fasb.org/us-gaap/2024</BaseTaxonomy>
    <BaseTaxonomy items="26">http://xbrl.sec.gov/dei/2024</BaseTaxonomy>
    <BaseTaxonomy items="4">http://xbrl.sec.gov/ecd/2024</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
