Ownership Submission
FORM 4
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940
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(Print or Type Responses)
1. Name and Address of Reporting Person *
Cysewski Gerald R
   2. Issuer Name and Ticker or Trading Symbol
CYANOTECH CORP [CYAN] 		5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
__X__ Director _____ 10% Owner
__X__ Officer (give title below) _____ Other (specify below)
CSO
(Last)
(First)
(Middle)
73-4460 QUEEN KAAHUMANU HWY #102		 3. Date of Earliest Transaction (Month/Day/Year)
04/02/2018
(Street)

KAILUA-KONA, HI 96740		 4. If Amendment, Date Original Filed(Month/Day/Year)
 6. Individual or Joint/Group Filing(Check Applicable Line)
_X_ Form filed by One Reporting Person
___ Form filed by More than One Reporting Person
(City)
(State)
(Zip)
Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security
(Instr. 3)		 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code
(Instr. 8)		 4. Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4 and 5)		 5. Amount of Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 3 and 4)		 6. Ownership Form: Direct (D) or Indirect (I)
(Instr. 4)		 7. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V Amount (A) or (D) Price
Cyanotech common stock 04/02/2018   M(6)   8,333 A $ 0 123,985 D  
Cyanotech common stock 04/02/2018   F(5)   3,130 D $ 5.1 120,855 D  
Cyanotech common stock               250 I Held by spouse

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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 3)		 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (Month/Day/Year) 3A. Deemed Execution Date, if any (Month/Day/Year) 4. Transaction Code
(Instr. 8)		 5. Number of Derivative Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4, and 5)		 6. Date Exercisable and Expiration Date
(Month/Day/Year)		 7. Title and Amount of Underlying Securities
(Instr. 3 and 4)		 8. Price of Derivative Security
(Instr. 5)		 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 4)		 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 4)		 11. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares
Restricted stock units (1)               (2)   (2) Cyanotech common stock 500   500 D  
Restricted stock units (1) 04/02/2018   M     8,333   (3)   (3) Cyanotech common stock 8,333 $ 0 16,667 D  
Cyanotech common stock options $ 2.08               (4) 04/29/2019 Cyanotech common stock 10,000   10,000 D  
Cyanotech common stock options $ 3.58               (4) 06/30/2021 Cyanotech common stock 12,000   12,000 D  
Cyanotech common stock options $ 3.82               (4) 08/27/2021 Cyanotech common stock 103,000   103,000 D  
Cyanotech common stock options $ 5.84               (4) 07/18/2022 Cyanotech common stock 12,500   12,500 D  

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
Cysewski Gerald R
73-4460 QUEEN KAAHUMANU HWY #102
KAILUA-KONA, HI 96740		   X     CSO  

Signatures

 /s/ Dan Sprague, by Power of Attorney   04/04/2018
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1) Each restricted stock unit represents the contingent right to receive one (1) share of Cyanotech common stock.
(2) The restricted stock units shall vest as to 167 shares on April 5, 2018, 167 shares on April 5, 2019 and 166 shares on April 5, 2020, in each case subject to the reporting person's continued service with Cyanotech on the vesting date.
(3) The restricted stock units shall vest as to 8,333 shares on March 31, 2018, 8,333 on March 31, 2019 and 8,334 on March 31, 2020, in each case subject to the reporting person's continued service with Cyanotech on the vesting date.
(4) Fully exercisable
(5) The reporting person is reporting the withholding by the issuer of 3,130 shares of common stock that vested on March 31, 2018 pursuant to the March 31, 2017 RSU grant, but that were not issued in order to satisfy the reporting persons tax withholding obligations in connection with the delivery of the converted common stock to the reporting person as of April 2, 2018.
(6) Represents the conversion upon vesting of restricted stock units into common stock.

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