Distribution and Relative Size of the Swim Bladder in Percina, With Comparisons to Etheostoma, Crystallaria, and Ammocrypta (Teleostei: Percidae)

The distribution of the swim bladder was examined in 20 species representing all four genera (Percina, Etheostoma, Crystallaria, and Ammocrypta) of darters (Etheostomatini). Including data on species examined in other studies, swim bladders have been found in 15 of 17 species of Percina, but were absent in Crystallaria asprella, Ammocrypta pellucida, and the 18 species of Etheostoma examined. Relative swim bladder length in Percina was shown to be positively correlated with body size. Although not statistically significant, swim bladder size also correlates with habitat (riffle, run, or pool) and swimming behavior (midwater or benthic).