40 nitrates I did a 5 gallon wc I wouldve done a 25, but I dont have any oceanic salt left
40 is deffinetly too high, but I would reccomend NOT doing a 25 gallon water change. Changing 25 gallons in a 55 gallon tank means you're replacing 50% of the water in the tank. That's going to be a drastic chemical shock to the fish as the levels of all the trace elements shift. I would reccomend doing a 10 gallon wc. And then another 10 wc a week later.
That aside, you're bioload is somewhat heavy for the tank in it's current state. This is what is causing your high nitrate levels. Your tank has not matured enough to handle that much life yet. If you can, I would try and return at least the 2 yellow tail damsels to the store.
IMO, your tank is also too young for either of the anenomes. even if they "look" healthy now, anenomes are slow to signs of stress, and by the time stress is evident, it's often too late to save them.
You number one asset in having a successful
SW tank, SaltwaterTeen, is going to be patience. And lots of it. You have to take things slow. You have to let your tank grow with you as you knowledge of the
SW hobby grows. Stick with it, follow our advice, and you'll have a beautiful healthy tank for years.