Over the years, many colleagues who were pleased, but were not familiar with the design and contents of FishBase have asked why we do not use it to cover other groups, for example, mollusks or crustaceans.

The alert user of FishBase will notice, however, that "covering groups other than fish" is easier said than done. What gives FishBase its ability to accommodate, in compact form, so much information on fish is the fact that it was designed to do this. Thus, the tables describing the morphology of the larval and adult forms can accommodate only finfish, and would be inappropriate for the description of crustaceans. Many other tables also contain fields that are specific to finfish, such as length types.

Duplicating such tables (one special set for every major group) would make the resulting database extremely unwieldy, with many tables or fields remaining empty for most species. Alternatively, one could conceive of reducing FishBase to those tables that would be similar among groups (for example, nomenclature, distribution, etc.). The result would be a database similar to FAO's SPECIESDAB (Coppola et al. 1994) which is indeed meant to eventually cover all aquatic groups of commercial importance, and which FishBase should not duplicate.