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Bioassays - Fewer bioassays were run on humpback chub than on the Colorado squawfish (Beleau and Bartosz 1981). In the comparisons that were made, the humpback was slightly more resistant to pesticides (DDT, parathion) than the Colorado squawfish and northern squawfish (DDT only). However, in comparisons of metal tests (Hg, Se), the humpback chub was less resistant than the Colorado squawfish, but either as resistant (hg) or slightly more resistant (Se) than the northern squawfish, LD50s of several exotic species, some now found in the Colorado River, were used for comparison with those determined for the humpback chub. However, no generalization across species and chemicals can be made. Food - Mayflies (Ephemeroptera) comprised about 77X and 33X of the main diets of YOY Gila sp. and YQY roundtail chub respectively (Jacobi and Jacobi 1981). Invertebrate remains comprised 54% and 72% of the mean diet of YOY and juvenile roundtail chub. In one stratum (VI) juvenile roundtail chub only consumed fish. Mayflies and invertebrate parts were found to be the major food items of the red shiner. Com- petition for food with the red shiner and roundtail may be a problem for YOY and juvenile humpback chub. Health - The health and condition of humpback chub in both the upper Colorado the Green Rivers appears to be good. Fish taken into captivity, however, have been lost to fungus and bacterial infections brought on by injury in handling and stress (Flagg 1981). Lesrnaea was often found on these fish in low numbers. The pathogens found in these rivers pose no threat to the general population. On the other hand, humpback chub from the Little Colorado River had a high incidence of Learnaea ( 50%) with up to seven parasites per fish (Kaeding and Zimmerman 1980). Kaeding (personal communication) also found sick adult humpback chub in 1981 following the spawning period. Subsequent examination of samples taken from these fish revealed a systemic bacterial infection (Flagg 1981). High TDS, crowding, and less than preferred conditions in the Little Colorado River have resulted in a stressed population of humpback chub which are more susceptible to parasites and diseases. Bonytail Chub Distribution and Abundance The apparent morphological variability of Gila spp. in the Colorado Basin makes any discussion of G. ele ans status highly speculative and open to considerable debate by the few knowledgeable professionals who frequently do not agree on the identification of specific individuals. This problem was aggravated by the fact that these experts weren't available to examine each Iive specimen collected in the field; that the classification criteria were developed from preserved specimens which, it has turned out, had practically no application to live specimens and tab, due to their status, they could not be freely sacrifice. A few senile specimens of bonytail chub continue to be collected from Lake Mohave in the Lower Colorado River Basin. These Lake Mohave