The fish specimens at the Natural History Museum Basel primarily date from the first half of the 20th century. They also include a few examples from Switzerland of species that are nowadays extinct.
The fish collection is relatively small, comprising over 6,500 alcohol-preserved specimens, and was never curated by fish researchers (ichthyologists). The specimens document a Swiss fish fauna that no longer exists in this composition. They include species such as the European river lamprey or the Atlantic salmon, which have now disappeared from Switzerland. The type material is of supraregional importance. The collection includes a total of 45 types of fish from Central Africa, Saudi Arabia, and Indonesia.