u/Potential-Spot-2734

Got this guy and a buddy yesterday but he now had that big red spot and I’m pretty sure he ate a piece of substrate but didn’t know for sure

Newley cycled tank fish are stressed out and idk what I’m doing wrong. I just did a 50% water change yesterday and do a 25 weekly but nitrites have just shot up to 5 this past week and idk what I did wrong