Upper and Middle Freshwater Reaches
The upper and middle sections of the Fitzroy support the bulk of the river's 23 resident freshwater species. These stretches are characterized by deep pools, rocky substrate, and the dramatic Kimberley landscape. Species like Spangled Perch, Bony Bream, Mouth Almighty, Western Rainbowfish, Hyrtl's Tandan, Freshwater Longtom, and the remarkable Fitzroy Glassfish are found throughout these reaches. Several species here are endemic to the Kimberley region and found nowhere else on Earth.

Lower Tidal and Estuarine Reaches
As the river approaches King Sound, it transitions into tidal, brackish water where marine and estuarine species push far inland. This is prime Barramundi country, and species like Tarpon (Ox-eye Herring), Bull Shark, Mullet (Greenback and Diamond), Lesser Salmon Catfish, Toothless Catfish, and Rendahl's Catfish are all present. Estuarine opportunists including Spotted Scat, Whipfin Silverbiddy, and Scaly Croaker are also found in these lower reaches. The critically endangered Freshwater Sawfish and Dwarf Sawfish have been recorded in this zone as well.

King Sound (River Mouth and Tidal Extension)
King Sound functions as a vast tidal extension of the Fitzroy River mouth and offers some of the most diverse saltwater fishing in the region. During the dry season, calm conditions open up access to numerous creeks and channels holding Barramundi, Salmon, Fingermark Perch, Mangrove Jack, Mulloway, Trevally, Cod, Catfish, and Sharks. Mudcrabs are also abundant throughout the Sound.