Hi everyone, hoping for some advice.

I recently set up (less than 2 weeks), a new 450L (120 gal) discus tank with 6 discus, 2 bristlenose, corydoras and a couple of other bottom fish. The tank was set up using mature water and a mature filter, so it's not cycling from scratch.

Here's my situation: I have a **separate 275L tank** that has been dealing with an ich outbreak. However, I have **never shared any equipment, water, nets or anything** between the two tanks, I've kept them completely separate.

Now, in the **new discus tank**, only **one** of my discus (pictured) seems to have a few **white spots**. The other 5 discus and all the bottom fish look completely fine, no spots, eating well, normal behavior.

My questions:

1. Does this look like ich to you, or could it be something else / part of the pattern?
2. If it's ich, could the discus have brought it in already incubated, even without cross-contamination?
3. Best treatment for a **planted discus tank,** heat only (30-32°C), or heat + medication? I'm cautious because discus are sensitive.
4. Should I be worried about the other fish even though they show no symptoms yet?
5. I have Faunamor - Tierarzneimittel from my other aquarium where i treated the other fishs

Water is warm (29°C), I'm running a Fluval FX4, with air stone. Tank is planted.

Thanks in advance for any help!

(claude help me write this because english not my first language)

Only ONE of my discus has white spots (ich?), the rest look fine. How should I treat?