I'm a little newbie at fish ownership so forgive me for any mistakes.
2 months ago, I got a 5 gallon tank (yes, I cycled it and all) with a betta and two Julii cory catfishes. Yesterday, unfortunately, one of my catfish passed away (which I assume was because I didn't feed it properly). I immediately did a small water change & vacuumed the gravel. After that, I went out and bought TWO more catfish to accompany my other one.
Today, I noticed I think my new catfishes look healthier than my previous one.
(PICTURES FOR REFERENCE)
My new one is on the left and my old one is on the right. My old catfish's colors seems to be faded. The new catfish has a visible black line along its body; while my old catfish's supposed line doesn't even look like a line anymore. Also, when my old catfish is resting, its top fin slightly droops to the side. Other than that, it seems to be fine and active.
Is my old cory healthy/okay? Should I be worried about it since my other one died?