You want a thin layer of substrate on the bottom of the tank to help the fish feel more comfortable. A picture on the back and some plastic plants would help too.
Is the fish still eating normally?
What does its poop look like?
How long has the problem gone on for?
It could be an internal protozoan infection, which normally causes fish to lose weight over a few weeks. They eat but not as much as normal, and do a stringy white poop. Metronidazole is the treatment of choice for internal protozoan infections.
Seachem does a medication called MetroPlex that contains Metronidazole.
Thank you. I have bare bottom quarantine, because I read that people don't recommend substrate, decor etc., cause the tank will be medicated and the med will sink into substrate and also to clean up the food debris fast. I have sand and gravel that I could use. But does it mean I should change the substrate in it every once in awhile then and vacuum uneaten food off of it daily?
This recent state has been going on for over a week. But his weight loss started about 3 weeks ago. I saw some weird mass in his belly one day and weeks later he started getting flat belly every day even if he ate so much. He also had white stringy poop with days of normal poop.
I treated main tank with every possible med like I said and nothing seemed to help, so that's why I quarantined him now. I did one more course of Esha NDx which is levamisole and closest to metro, cause I can't get metro in EU.
Now I am treating with Esha 2000 and Esha Exit. I also gave him salt baths a few days ago, but there was no improvement.
Here's a photo from a few weeks ago when I first noticed something weird in his belly.
He is still eating but with little appetite. I feel like he only eats when food floats but not when it touches the floor, like he's disturbed with reflection in there?