Cherub Angel dead this morning

[Beezwax404]

I bought a cherub angel 6 days ago to add to my BC29 with a ocellaris and a royal gramma. The angel chased my giant gramma out of his caves and took over the rock work abd was stressing the gramma out. So two nights ago i rescaped the aquarium and since i did that the gramma was flasging and had white dots and the angel got a bunch of tiny dusting of dots. The angel looked bad but acted fine other than hiding alot. He wad eating alot. Last night i checked my water param and everything was perfect except i had .25ppm nitrite. This morning the angel was dead and he looks pale on his belly and part of the gill area. Any idea what this could be? He was very healthy at the fish store. One pic is him at the LFS the day i bought him and the other is the body. Please help

 

[happyhourhero]

Really hard to say. A lot of the time, lfs run super low salinity or copper so it masks illness. Once you get the fish into normal sg ranges, sometimes things pop up which is why so many advocate for quarantine.