Historically, fishes representing 16 families and 74 species were collected from seven sites along the main stream of The Blue River. Included in this catch were nine species of darters (Percidae): greenside, rainbow, bluebreast, fantail, johnny, orangethroat, banded, spotted and variegate. Also included in this list were several species of game fish such as the smallmouth bass, largemouth bass, bluegill, white crappie, rockbass and longear sunfish. By far the most abundant family caught was the shiner/minnow family (Cyprinidae). A total of 22 species of this family were tallied.
The Blue River has always been regarded to be one of the healthiest streams in Indiana. Many indicators, both biotic and abiotic, support this assertion. &nbso;Three abiotic indicators are: (1) The stream is fed promarily by underground water sources. These sources are much cleaner than water from surface run-off due to the filtering effect of soil (2) The enormous amount of pooling, indicative of parts of The Blue River, allows sediment to settle, thus clearing the water (3) The lack of glaciation of the area allowed the aquatic habitiats to remain intact during the last ice ages.
As mentioned above, this study resulted in the collection of many darter species at almost every site along The Blue River. The Rothrock's Mill site was the exception to this primarily because of the lack of habitat in the area. This site can best be described as large shallow pools over bedrock with glide and run channels connecting them. This is hardly prime darter habitat. Overall, however, the darters comprised 61% of our total fish catches. Of the nine darter species taken , the spotted darter (E. maculatum) was the most characteristic and abundant species, with 66.54 per 100 square feet being caught. This is a different result than what was found in 1986. In this study banded darters (E. zonale) were more numerous with 70 per 100 square feet being collected and only 18 spotted darters per 100 square feet. This cause for large differences is hard to decipher because seine hauls were conducted at the same sites during the same time of year. The only feasible explanation can be an increasing population or migration of the darters to a more desirable habitat. The decrease in number of other darter species compared to those caught in 1986 could be due to an increasing spotted darter population.