The true mailed catfishes, with around 150 described species and at least as many not yet classified by science, form a highly complex group. All things considered, research into the systematic of these fishes, which are apparently all very closely related to one another, is very much in its infancy. Now, it is true that in the aquarium hobby it is not the scientific name of a species, but the live fish, that is the center of interest. However, it is sometimes necessary to be able to indicate what species we are talking about, and hence C-numbers were brought into being in the magazine DATZ (=Die Aquarien und Terrarienzeitschrift), for identifying Corydoradinae that have been imported but not yet identified. The first C-numbers appeared in the DATZ of 12/1993. Since then a number of species have either been described as new species or identified as existing described species. The majority of C-numbers, however, remain just as difficult to classify as in the past. By the time the AQUALOG All Corydoras (ISBN 393[zasłonięte]2138) was published in 1996, there was already C-numbers 1 to 46. In the meantime we have reached C132 and there is no end in sight. But we nevertheless feel it makes sense to publish this complete list of all the C-numbers to date, compiled in line with the most recent knowledge. With over 270 photos, a must for the Corydoras lovers.