One of my Blue Diamond Discus has turned dark blue and is malnourished. I treated him with Prazi Pro doses (two in two weeks). While he has been eating a little better, he still looks the same. Vienna aquarium said to try a third treatment. A FB Group I’m in said to treat with Metronidazole (I have no idea where to get that from). Any thoughts/suggestions?
Also, I’ve been treated my water with Seachem Safe for water changes... but I have never been putting a Stress Coat into the tank. Should I use a Stress coat as well?

Normal

Current
tank size
tank mates
nitrate reading
ammonia reading
temperature
water change schedule
how many feedings per day and of what foods
you can get metro online off of amazon . comes in powder form. wouldn’t recommend meds right away imo with discus. I’ve used prazipro in the past but it doesn’t work well for some prazi resistant internal parasites.
All my readings are normal... water changes at least once a week. Temp is 83 with my plants. I have discus, schools of rummy nose tetra and Congo tetras. Also three Clown Loaches and three YoYo Loaches. I just noticed yesterday the YoYo was sucking at the discus.
@Jae M. It’s not recommended to keep any type of algae (sucking) fish with discus because they’re known to go after discus slime coat. hard to help much with plants being low temp. Without plants you can raise temp to 90f. if you have another tank you can move the loaches or the discus to I would recommend that to start.
@HunterMcLaughlin I will look into the metro... I was going to up my water changes and use Stress Coat? Thoughts? I‘lol have to check if the tetras can take anything warmer than 82...
Fenbendozal is a good parasite remedy for internal parasites but it’s hard to find.