Fish (Class Pisces) found at Florissant include suckers, bowfins, catfishes, and pirate perches. Many of the fishes found at Florissant could tolerate poor water conditions, such as the bowfin and catfish. Modern bowfin are able to use their air bladder as an auxiliary lung by "gulping" air at the surface of the water, much in the same way as do carp, catfish, and gar.
In addition to the identifiable fish fossils listed above, one currently unidentified fish fossil and what appears to be fish dung have been found at Florissant Fossil Beds.