The $(z,k)$--equivalence of matrices over imaginary Euclideanquadratic rings is investigated. The classes of matrices overthese rings are selected for which the standard form with respectto $(z,k)$--equivalence is uniquely defined and equal to the Smithnormal form. It is established that the number of standard formsover imaginary Euclidean quadratic rings is finite. Bounds for anumber of standard forms are established.