discus in a 55

Hi Ben,
3 discus is not a good number to keep - you would very likely be inviting undesirable pecking order/aggression issues. Get 5 discus for your 55 gal, and don't keep any other any other fish in with them - particularly the red-tailed shark which is not a good discus tankmate, and the loach may not be either.

And since you plan for your tank to be well planted, with substrate & lots of dw, that can cause you problems unless you maintain a very good tank cleansing routine & frequent large wcs, at least 3 X a week.

Keep it simple, without heavy plantings or lots of DW, so as to allow you to do a good vacuuming job, and give the discus a reasonable amount of swimming space. You'll need to maintain high quality water conditions for discus to thrive, and it's always best to become familiar with discus traits & behaviors in a BB, or very lowly-decorated tank for a few months, before you begin complicating things by adding more plantings & decor.

I believe it would help you to have a read of my Beginner's Guide to Getting Started with Discus, located here as a sticky in the Cichlids section, Angel Fish & Discus sub-section.

Best of luck to you and don't hesitate to PM me if I can be of any further help.

If you get mature, adult discus, yes you can get by with only one WC a week.

But between 3" to 5" in size, they should have at least 2 large wcs per week. Young fish or small juvies should have the benefit of daily wcs to grow out properly.

And keep in mind that the important thing with discus is that, even though a well planted tank environment will generally maintain good quality water conditions from a "chemical" standpoint, that type of environment is nonetheless not conducive to maintaining squeaky clean tank conditions, with a minimum accumulation of detritus, decomposing plant matter & food, fish waste, etc. - which the plants will be quite happy with, but not necessarily the discus.
This type of environment is very difficult to vacuum properly, and allows for build-up of matter that discus may not thrive in. Lots of good, fresh clean water is the key for discus to do well.
Yes, discus do in fact take a little extra work, but it's a satisfying challenge in keeping these beautiful fish healthy.

2" to 3" discus are pretty small juvies, and I really feel they would be better off getting a small daily wc, rather than larger changes only twice a week, at least for the first approx. 2 months after you get them.

Your food list sounds A-OK. And you don't need to feed them at the same time, every time. They would do better though, getting several smaller feedings a day, rather than just one or two larger feedings, at least until they get to about 4". If your work day prohibits 4 -6 feedings at various times every day, try feeding once or twice every morning before you leave home, and then 2 to 4 times in the evenings when you're back at home, spaced an hour or two apart would be fine.
In the past I have fed small juvies small amounts, up to 10 X a day, giving them some food every time I'm passing by the tank, every hour ot two (of course, you can do that when you're retired, as I am -lol).

Relax - it's generally quite normal for discus to take up to 3 weeks or more to become fully accustomed to, and comforfortable in, a new environmenmt/new surroundings. In fact, it's not unusual for them to also not begin eating for several days, up to a week or more. Yes, they will be skittish and somewhat stressed for a while - give them some time - I'm sure you'll notice a change for the better in just a few days.
Not to worry.
And the 4 spots you noticed on one fish - again don't be concerned, and don't even think about medicating yet - it's not likely ich at all.
4" discus are good-sized fish, with reasonably well-developed immune systems, and they should be just fine. Hopefully you got good quality, healthy stock from a responsible, experienced source. If so, you should have nothing to worry about.

Don't be uptight about asking many questions - that's a real good sign from a new discus-keeper - that's of course how one learns - how I learned.
I'm quite sure your discus will be behaving a whole lot better in a day or two, and you'll feel better too.