v3.25.2
Document And Entity Information - USD ($)
 12 Months Ended
Mar. 31, 2025
Jun. 13, 2025
Sep. 30, 2024
Document Information [Line Items]      
Entity Central Index Key 0000768408    
Entity Registrant Name Cyanotech Corp    
Amendment Flag false    
Current Fiscal Year End Date --03-31    
Document Fiscal Period Focus FY    
Document Fiscal Year Focus 2025    
Document Type 10-K    
Document Annual Report true    
Document Period End Date Mar. 31, 2025    
Document Transition Report false    
Entity File Number 0-14602    
Entity Incorporation, State or Country Code NV    
Entity Tax Identification Number 91-1206026    
Entity Address, Address Line One 73-4460 Queen Kaahumanu Highway, Suite 102    
Entity Address, City or Town Kailua-Kona    
Entity Address, State or Province HI    
Entity Address, Postal Zip Code 96740    
City Area Code 808    
Local Phone Number 326-1353    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Filer Category Non-accelerated Filer    
Entity Small Business true    
Entity Emerging Growth Company false    
ICFR Auditor Attestation Flag true    
Document Financial Statement Error Correction [Flag] false    
Entity Shell Company false    
Entity Public Float     $ 2,977,140.4
Entity Common Stock, Shares Outstanding   7,232,217  
Auditor Name BPM LLP    
Auditor Location Walnut Creek, California    
Auditor Firm ID 207