It looks like ich. The tank needs to be treated. This is why qt new fish for atleast 3-4wks is so important.
.3% salinity is 11.4grams per gallon. It needs to be predissolved in conditioned water. The salt solution needs to be added gradually over 48hrs. Very gradually! Water changes should be done frequently along with good gravel vacs. For a 50% wc
, add back half of the original dose predissolved along with the new water. The salinity needs to be maintained for one week AFTER the last spot is gone. Keep a daily check on your parameters as you may see spikes in toxins. Please ask if you have questions!