- Joined
- Apr 19, 2019
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This does sound eerily like a parasite. These days. if you don't quarantine, the odds of adding velvet to your tank with 4 fish added is probably almost 100%. Velvet isn't a parasite you can manage, the vast majority of the time. It's much more common than it used to be, leading many to begin quarantining. Uronema is also becoming far more common.
That fish does look a bit beat up. A freshwater dip on a remaining fish in a dark bucket would be my first step, you're looking for small "sesame seed" looking things dropping off, these would be flukes, most likely. This doesn't mean you don't have other issues but it's a starting point. Flukes can eat at the fins, but I am leaning toward that being another fish picking on it, pre or postmortem.
Sorry for the trouble
How long does it take for flukes to kill a fish?