An \(\mathbb {F}_q\) -linear code of minimum distance d is called complete if it is not contained in a larger \(\mathbb {F}_q\) -linear code of minimum distance d. In this paper, we classify \(\mathbb {F}_q\) -linear complete symmetric rank-distance codes in \(M_{3\times 3}(\mathbb {F}_q)\) up to equivalence. This includes the classification of \(\mathbb {F}_q\) -linear maximum symmetric rank-distance codes in \(M_{3\times 3}(\mathbb {F}_q)\) . Our approach is mainly geometric, and our results contribute towards the classification of nets of conics in \(\textrm{PG}(2, q)\) .