Ichthyology is the branch of zoology studies fishes. This includes the bony fishes (Osteichthyes), the cartilaginous fishes (Chondrichthyes) such as sharks and rays, and the jawless fishes (Agnatha).
... dB is the abbreviation for Decibel; see Bel
DB is a French automobile maker; see DB (car)
DB is the abbreviation for Deutsche Bahn, the major German railway company
...