Exhibit 21

TETRA Technologies, Inc.

List of Subsidiaries or Other Related Entities

December 31, 2008

Compressco, Inc.

Compressco Canada, Inc.

Compressco Field Services, Inc.

Compressco Field Services International, LLC

Compressco International, LLC

Compressco Leasing, LLC

Compressco Mexico investment I. LLC

Compressco Mexico Investment II. LLC

Compressco de Mexico, S de RL de CV (1)

Compressco Partners GP Inc.

Compressco Partners, L.P. (2)

Compressco de Argentina SRL (3)

Compressco Partners Operating, LLC

Compressco Partners Manufacturing, LLC

Compressco Testing, L.L.C.

Providence Natural Gas, Inc.

TETRA Applied Holding Company

TETRA Applied Technologies, LLC

EPIC Diving & Marine Services, LLC

Maritech Resources, Inc.

Maritech Holdings, Inc.

Maritech Louisiana, LLC

Maritech Partner, LLC

Maritech Timbalier Bay, LP (4)

T-Production Testing, LLC

TETRA Production Testing Services, LLC

Beacon Resources, L.L.C.

TETRA Financial Services, Inc.

TETRA-Hamilton Frac Water Services, LLC

TETRA International Incorporated

Ahmad Albinali & TETRA Arabia Company Ltd. (LLC) (5)

Production Enhancement México, S.A. de C.V. (6)

TETRA Angola Investments, LLC

TETRA de Mexico, S.A. de C.V. (6)

TETRA International Holdings, B.V.

T-International Holdings C.V. (7)

TETRA Netherlands, B.V.

TETRA Chemicals Europe AB

TETRA Chemicals Europe Oy

Kemax B.V. (8)

TETRA Completion Services Holding B.V.

TETRA Completion Services B.V. (9)

TETRA Technologies de Mexico, S.A. de C.V. (6)

TETRA Technologies de Venezuela, S.A.

TETRA Technologies do Brasil, Limitada (6)

TETRA Technologies (U.K.) Limited

TETRA International Employment Ltd. Co.

TETRA Technologies Nigeria Limited

TETRA Medit Oil Services (10)

TETRA Madeira, Lda.

TETRA Micronutrients, Inc.

TETRA Technologies Australia Pty Ltd

TETRA Process Services, L.C.

(1)   Compressco Mexico Investment I. LLC owns 51% and Compressco Mexico Investment II. LLC owns 49%.

(2)   Compressco Field Services, Inc. owns 99.9% and Compressco Partners GP Inc. owns 0.1%.

(3)   Compressco Field Services, Inc. owns 90.0% and TETRA International Incorporated owns 10.0%.

(4)   Maritech Partner, LLC owns 50.0% and Maritech Louisiana, LLC owns 50.0%.

(5)   TETRA International Incorporated owns 50.0%.

(6)   TETRA International Incorporated owns 99.998% and TETRA Technologies, Inc. owns .002%.

(7)   TETRA International Holdings, B.V. owns 96.0% and TETRA International Incorporated owns 4.0%.

(8)   TETRA Netherlands, B.V. owns 50.0025%.

(9)   TETRA Completion Services Holding B.V. owns 85.0%.

(10)   TETRA International Incorporated owns 65%.