Definitely ich on the trigger - I’m not sure I see anything on the grouper in the photos, but you would want to treat him too.
Unless you can remove the starfish from any tank that has fish for 76 days, there aren’t any in tank treatment options that will cure ich and keep the star alive.
You should be feeding your fish always. If the star is being pulled, hyposalinity is your best option for the display tank. Rock and sand will absorb copper, making dosing a nightmare.
Assuming you are using api, 0.25 ammonia is possibly a misread, but the 80 nitrates is an indicator that you need to up your water change rates. In a reef you don’t want those going above 20.
Ok so I’ll add more salt mix and I’m doing a waterchange anyways in two days I transferred the Star today and am gettin a copper medication called copper safe by a company called fritz is that a good copper medication will it work
Take this as just my experience but I try not to medicate if I don't have to. If the fish are stressed from the high nitrates, they are more susceptible to disease and parasites. I would do a series of as large a water change as you can to get the nitrates down. If you can do a 90% water change I would. If you only do a 50%, you'd need to do 3 50% to get down to 10ppm. But I'd get the parameters in order to reduce stress. While you're at it, it wont hurt to do the hyposalinity. The biggest thing in my opinion is keeping the fish eating. If they stop eating, then I would try to add some garlic oil to the food. It will encourage them to eat it and help keep them feed. Once the stress is gone, they should be able to fight off the ich better. I'm not a fan of copper if I can help it. I managed to save a single leopard wrasse from a 120G tank full of fish that got red velvet once, so it definitely has it's uses and I'd keep it on hand. Again, this is one random guy on the internet's experience. I'm definitely not an expert.
You should have copper on hand, but in this case hypo really is the best option. Copper shouldn’t be dosed to the dt, and these fish are too big to go in a small qt. Over the next few days, lower the salinity in the dt to 1.009, and get the star out of there.
Copper safe dosed to 2.0+ ppm in a hospital tank works great. Dropping specific gravity to 1.009 can work well in a display. Those are 2 good options. Pick 1.