If anyone can identify what might be wrong with the swordtail in the picture I'd really appreciate it. A couple months ago another swordtail had what looked like this same condition, but only in a single spot, not multiple. At the time I thought it was simply an injured scale, and it got better within days. Now I don't know what to think.
She lives in a 55 gallon tank with about 25 similarly-sized fish, two yoyo loaches, a bristlenose pleco, and a bunch of tiny "pest" snails that snuck in on plants, as it's a planted tank.
One of her sisters has a single discoloration spot that looks the same as this. A couple of the other fish have small tears in their tails or top fin, but no signs of fin rot. The biggest one, who happens to be everyone's mother and the oldest of the bunch, has the tiniest white spot on her top fin. It's so small I can't tell if it's fuzzy or anything.
The water parameters are all great except for Nitrate levels, which are just barely above "not a problem whatsoever" levels at about 4 ppm. Ammonia and Nitrites are nominal.
The tank has 2 submerged filters and is kept at 77°F, but I've lowered it to 76 since discovering this, as my first thought was that it might be columnaris, which does better in warmer temperatures.
The tank is well established, and these fish have lived in it for over a year. I've been keeping fish for about 4 years now and have seen a few different illnesses, but I can't even find a picture online that looks like this. It's early and I hope it turns out to be nothing serious, but in case it is I want to try and get ahead of it.
Thanks for any help you can give me.
I'll also try to fill out the template below in case someone asks about something I haven't mentioned. It's probably easier to find information this way too.
Running for over a year
2 bubble filters fed by air pump, smaller submerged filter up top used as a "fish treadmill"
2 heaters, temperature controlled within 1°F
Temperature was 77°F, now set to 76°F
25 female (for now) swordtails averaging about 1.5 inches in length, 2 yoyo loaches, the biggest female bristlenose pleco I've ever seen (6.5 inches) and hundreds of tiny "pest" snails. I think they're malaysian trumpet snails? They're only about 5 mm long at most.
Water is changed weekly
30-40% water changes
Aqueon Conditioner used to treat water
Substrate is vacuumed
*Parameters - Very Important
Tank was cycled
Water was tested with API Freshwater Master Test Kit, the kind where you add drops of chemicals.
What are your parameters? We need to know the exact numbers, not just “fine” or “safe”.
Ammonia: 0 (or at least nothing that registers on the test kit)
Nitrate: 5 ppm
Fish are fed flakes and granules 3 days a week, frozen bloodworms once a week, and peas once a week. They're fasted on Tuesdays and Fridays, and there's almost always a couple slices of vegetable (cucumber or zucchini) in there, which are replaced every few days.
Illness & Symptoms
I've had the sick fish for over a year. I think 14-16 months.
I noticed the symptoms only yesterday.
She has patches of white discoloration on the scales above her head.
No treatment has been started yet.
The fish was born in this aquarium.
Behavior has not changed.