Because North Dakota saline pothole lakes offer a good potential for fish culture and the anticipation of increased salinity from return flows from the Garrison Diversion Irrigation Project, salinity tolerance of the fathead minnow, northern pike, and walleye were evaluated. Also studied was the influence of the levels of dissolved solids on egg and sac fry survival and the fathead minnow, northern pike, and walleye were evaluated. Also studied was the influence of the levels of dissolved solids on egg and sac fry survival and the fathead minnow's food habits. Laboratory experiments indicated that in water of 1300 micromhos, eggs of fathead minnow, northern pike and walleye hatched well, but when salinity reached 4000 micromhos, there was no hatching of walleye, a very poor hatch of northern pike eggs, but a good hatch of fathead minnow eggs. No northern pike sac fry survived in water of 6000 micromhos and all fathead minnow sac fry (about 1%) surviving in 12,000 micromhos had physical abnormalities. Water in saline lakes with an early summer total dissolved solid concentration of 7000 ppm was not detrimental to fathead minnow reproduction and growth.