What’s wrong with my fish?

Hi! I’m new to the site and posting in hopes of getting some assistance with my fish. I had a cardinal tetra die yesterday. Before it passed, it started losing color around its dorsum and twitching around the tank. Less than 24 hrs after I noticed the symptoms, it passed. I read in a forum that similar symptoms could be columnaris disease. I started treating my whole tank yesterday with melafix. This morning I saw another fish (one of my rummy nose) starting to display similar behaviors, loss of color around its caudal, washed out, injured- looking, operculum flaring, and gulping a lot at the bottom of my tank. Are there any other thoughts/ suggestions on what could be going on and how to treat?

Water chemistry testing at:
pH 6.6
Ammonia 0
Nitrite 0
Nitrate 5 ppm
Temp 74.5 F

Thanks!

Bbj_ said:

Hi! I’m new to the site and posting in hopes of getting some assistance with my fish. I had a cardinal tetra die yesterday. Before it passed, it started losing color around its dorsum and twitching around the tank. Less than 24 hrs after I noticed the symptoms, it passed. I read in a forum that similar symptoms could be columnaris disease. I started treating my whole tank yesterday with melafix. This morning I saw another fish (one of my rummy nose) starting to display similar behaviors, loss of color around its caudal, washed out, injured- looking, operculum flaring, and gulping a lot at the bottom of my tank. Are there any other thoughts/ suggestions on what could be going on and how to treat?

Water chemistry testing at:
pH 6.6
Ammonia 0
Nitrite 0
Nitrate 5 ppm
Temp 74.5

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that is weird the only disease I would think that could be is columnaris disease I would just keep treating for it and see what happens in 2-3 days

What is your water change routine?

Melafix is mildly antiseptic and would not treat Columnaris.

GaryE said:

What is your water change routine?

Melafix is mildly antiseptic and would not treat Columnaris.

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I did a 40% water change yesterday. My tank is new but I let it cycle for 7-8 weeks, tested the water chem until it was 6.6 pH, 0 ammonia, 0 nitrite and below 15 ppm nitrate. I’ve had fish in it for about 6 days. The rummies and cardinals were added most recent (this is 3rd day). It’s a planted tank.

The first 3 weeks after fish come from the store are the 'quarantine zone'. Things happen as a result of what nhappened to them en route to your place. Coming from crowded farms where disease exposure is possible, through the stress of travel, etc, a certain number may die. Rummy noses are notoriously sensitive and fragile. Cardinals less so, but you are still in the fish quarantine period so you may have simple bad luck.

I sound like a broken record [for those who remember "records" lol], but do not be hasty to start using "medications." Diagnosing disease is extremely difficult with fish, as there are so many symptoms that are common to more than one actual disease or health issue. And every additive to the water will get inside the fish and cause stress at the very least. And stress is the cause of more than 90% of all aquarium fish disease issues. If the issue can be fairly well identified, and a treatment is the most effective and safest for those particular fish, OK. But few of us can say this with such certainty.

Characins are especially sensitive to any chemical/medicine in the water. I would do a major water change, another tomorrow, maybe even a third day. By major I mean 70% of the tank volume. Do a thorough clean of the substrate at each of these. Keep the filter clean. This alone can be enough, depending upon the issue.

Columnaris was mentioned, this is a catch-all diagnosis and rarely is it the actual issue. I had it once, at least I think it was, it was certainly a killing bacterial infection that spread rapidly and was dealt with advice from a marine biologist. But clean water is the real preventative for most problems. Avoid stress.