An experiment was carried out to investigate the effect of crude sea salt at different salinities and with different concentrations of added minerals on the population growth of Brachionus plicatilis. The study was conducted under laboratory conditions (24 ± 2 °C), with an initial culture density of 200 ind./mL in a 3 L plastic jar containing 2 L of water and fed with baker’s yeast. The experiment consisted of 10 treatments with salinities of 2‰, 4‰, 6‰, 8‰, and 10‰, with and without mineral supplementation. Each treatment was repeated 3 times and cultured for 9 days. The water in each culture jar was replaced every day. After renewing the water, minerals were added to the culture jars at 0.25 mg/L. The results showed that the rotifers were able to survive at salinities from 2 to 10‰, but at a salinity of 2‰, the stocking density gradually decreased during culturing. The rotifer density increased more slowly at 4‰ salinity than at higher salinities. Minerals had an effect on the rotifer population growth at salinities of 6‰ or less, but no effect was observed at salinities from 8–10‰.