Gila cypha

Humpback chub

Family: Unknown · Class: Unknown · Order: Unknown

Conservation status: Threatened

The humpback chub is a medium-sized member of the minnow family that attains a total length of 1.5 feet (480 mm) and may reach weights of 2.6 pounds (1.2 kg). Adults are distinguished by enlarged nuchal humps that rise abruptly behind the head and laterally compressed, fusiform bodies that taper toward slender tails. Juveniles display greenish backs, silvery sides, and whitish bellies, while adults develop grayish-green backs and sides that fade to whitish bellies (USFWS). The humpback chub is endemic to the Colorado River basin, where it evolved approximately 3.5 million years ago. The species was first described from a specimen caught in 1933 near Bright Angel Creek in Grand Canyon, making it one of the last large fish species described in North America (USFWS). Historically, the species ranged throughout Arizona, Colorado, Utah, and Wyoming within the Colorado River system. Current populations are restricted to warm-water canyon areas of the Colorado River basin, with significant populations persisting in Arizona and Utah. This species inhabits swift, turbulent whitewaters found in canyon-bound sections of the Colorado River system. Humpback chub are uniquely adapted to these challenging hydraulic conditions, utilizing eddies, backwaters, and nearshore areas where current velocities are reduced. The species typically occupies warm-water reaches where temperatures can exceed 20°C, distinguishing its habitat preferences from cold-water trout zones. Humpback chub are closely related to bonytail (Gila elegans) and roundtail chub (Gila robusta), with which they co-occur and occasionally hybridize while maintaining species-specific characteristics. Spawning likely occurs in spring over rocky substrates, similar to related Gila species. The species' reproductive ecology and feeding habits in wild populations remain less well-documented than those of many other native fishes. Originally listed as endangered under the Endangered Species Act in 1967, the humpback chub was reclassified from endangered to threatened status in 2021 due to successful recovery efforts (USFWS). This downlisting reflects population improvements, particularly in the Little Colorado River tributary system and mainstem Colorado River in Grand Canyon. However, the species faces ongoing threats from flow regulation and habitat modification caused by large dams, predation by nonnative fishes, water diversions, and hybridization with related Gila species. Climate change and continued water management operations in the Colorado River basin present additional challenges. The species remains protected under the Endangered Species Act as threatened wherever found, with continued monitoring and adaptive management programs supporting its recovery in Arizona and Utah populations as of December 2025.

Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, and more.