Date of this Version
Of 14 species of freshwater fishes held in cages in one or more of 13 alkaline lakes and ponds in Nebraska, few species survived more than a month where carbonate alkalinity, mostly as compounds of Na2C03 and KC03, was above 300 mg/liter. Of the 14 species tested, Sacramento perch (Archoplites interruptus), fathead minnow (Pimephales promelas), northern pike (Esox lucius), and the black bullhead (lctalurus melas), were the most tolerant of alkaline environments. Most centrachid fishes except A. interruptusand the green sunfish (Lepomis cyanel!us), did not survive more than a month in alkaline waters greater than 950 mg/liter total alkalinity. A lake classification index for slightly alkaline to strongly alkaline environments is presented, along with suggested fish species for introduction into such waters.