Yes I had corals and fish live in 3.8 po4 levels .I dont think it a problem with fish but it does stress the corals out but they get us to it.Sps will loose colors and turn brown
do a water change and add phosban media my bros tanks po4 hit F'ing 50! He lost only some fish I believe 3 or 4. My po4 was 2.5 not too long ago and after doing a wc and adding media all was well with no losses of any kind. Animals adapt.