You have asked whether the Fish Commission may refuse to renew the artificial propagation license *395of a commercial fish hatchery operator on the ground that he has been charged by the Commonwealth with violation of the laws relative to erection of obstructions in streams even though no final disposition has been made of this charge.
The Fish Commission, being a statutory agency, has no powers except those specifically given to it by the legislature or necessarily implied. The commission’s authority to issue artificial propagation licenses is contained in section 170 of The Fish Law of May 2, 1925, P. L. 448, as amended, 30 PS §170, which states:
“The Board is authorized to issue an artificial propagation license for the propagation of all species of trout and all species of basses, upon a written application therefor signed by the applicant and upon the payment to such Board of the sum of twenty-five dollars; for the propagation of gold fish, the sum of five dollars; and for any other species of fish, the sum of five dollars: Provided, that a person licensed to propagate bait-fish may also propagate and sell fish-bait.”
If the applicant meets these requirements, and our review indicates they are the only requirements established by the legislature, issuance of the license is mandatory and the commission has no authority to refuse it. The establishment by the legislature of these criteria, namely signed application and payment, and the absence of any provision in the act giving the commission additional authority to make regulations respecting such licenses, together serve to exclude any other criteria for issuance of the license. “Expressio unius est exclusio alterius”: Commonwealth ex rel. Maurer v. Witkin, 344 Pa. 191 (1942).
Further limitation of the commission’s authority is contained in The Administrative Code amendment of April 25, 1949, PL 729, sec. 8, which provides that licenses may be issued “under such conditions and *396upon payment of such fees as may from time to time be authorized by law”.
The commission is authorized, under section 180 of The Fish Law, to revoke licenses under specified conditions. Section 180 reads as follows:
“Any person violating any provision of this article shall on conviction, in the manner provided by chapter fourteen of this act, be sentenced to pay a fine of one hundred dollars.
“In addition to such penalty, the license of such person may be revoked for one year for the first offense, and two or more years for the second offense, at the discretion of the Board.”
Since the applicant’s alleged violation was not charged under The Fish Law, but under another statute, this provision would not be applicable.
For these reasons it is our opinion, and you are hereby advised, that the Fish Commission has no authority to suspend, revoke or refuse to issue an artificial propagation license to an applicant who has met the statutory requirements therefor and has not been convicted of any offense under the applicable sections of the Fish Law.