- BAH
- Bahamas Islands
- Baikal Lake
- Balearic Islands
- Baltic Sea
- barbel
- basibranchials
- bathyale
- bathypelagic
- beak
- beard
- behavior
- beloniformes
- benthic
- benthopelagic
- Bermuda Islands
- bicolored
- bicuspid
- bifid
- bifurcate
- bilateral
- bilateral compressed
- bill
- billfishes
- bilobed
- bioluminescence
- bipolar
- Biscay Gulf of
- biserial
- bisubtropical
- bitemperate
- bivalves
- bladder
- blood
- BMNH
- BOC
- bone
- bony fishes
- bony stay
- boreal
- boreoaectic
- bottom living
- BPBM
- brackish
- branched rays
- branchial
- branchiostegal membrane
- branchiostegal rays
- breast
- breed
- breeding
- bristles
- brood
- brooding
- bryozoa
- buccal
- bucklers
- Bulb
- burrow