藍首亞口魚（學名：Catostomus discobolus）為輻鰭魚綱鯉形目亞口魚科的其中一種，為溫帶淡水魚，分布於北美洲美國懷俄明州、愛達荷州蛇河、懷俄明州、猶他州巴那維利湖向南流經科羅拉多河上游流域[2][3][4][5][6][7][8]，本魚體呈圓柱形，口下位成吸盤狀，頂部呈現深綠色或深銀色，底部呈現淺黃色，側線鱗70-100枚，在繁殖過程中，雄魚的大頭頂部會出現藍色斑塊，下鰭會變成黃色或橙色，並帶有紅色或玫瑰色側線，體長可達41公分，棲息在溪流底層水域，可適應各種環境，從山區冰冷的溪流到沙漠地區，白天會待在淺溪流，晚上覓食，繁殖期4至7月。
Arizona Game and Fish Department. 1988. Threatened Native Wildlife in Arizona. Arizona Game and Fish Department Publication. Phoenix, Arizona. p. 8.
Arizona Game and Fish Department. In prep. Wildlife of special concern in Arizona. Arizona Game and Fish Department Publication. Phoenix, Arizona. 32 pp.
Arizona Game and Fish Department Native Fish Diversity Review. 1995. Tempe, Arizona.
Beyers, D.W. et al. 2001. Habitat Use and Movements of Bluehead Sucker, Flannelmouth Sucker, and Roundtail Chub in the Colorado River. Larval Fish Laboratory, Colorado State University, Fort Collins, CO.
Cope, E.D. 1872. Recent reptiles and fishes in U.S. Geologic Survey of Wyoming and contiguous territory. Special reports Part IV:432-442.
Crabtree, C.B., and D.G. Buth. 1987. Biochemical systematics of the catostomid genus Catostomus: assessment of C. clarki, C. plebeius and C. discobolus including the Zuni Sucker, C.d. yarrowi. Copeia 1987:843-854.
Eddy, S. and J.C. Underhill. 1978. How to know the freshwater fishes, third edition. Wm. C. Brown Company, Dubuque, IA.
