General Disease question - maintenance

[FredF]

I have several  cardinal tetras that seem to have fungal infections.  Right now I am treating with medicated kanaplex food to see if that helps.  But my question is more general, about why this is coming up.  Here are the water parameters.  

ph 6.8-7.0, Ammonia and Nitrite 0 ppm, Nitrate 10-15 PPM, KH 40-60 PPM, GH above 150PPM, but below 300PPM

The above parameters, don't change.  I keep the water at 78.  I have a fluval 407 cannister filter, and I run an airstone in the tank.  I have fluval stratum in the background for plants, and sand in the foreground.  The tank has been established for nearly 6 months.  It's heavily planted in the background and midground.  Current inhabitants are:

12 cardinal tetras 10 rummynose tetras, 9 bronze corys, 1 SAE, 1 Bristlenose Pleco, some amano shrimp and 3 otos.

None of the other fish are affected, and all seem to be doing quite well.  I have a couple theories that I wanted to banter as to why this might be a problem and get some educated thoughts.

1. The water is simply too hard for the cardinal tetras, even with the low pH, causing long term health problems

2. I'm changing too much water.  I change 50% 1x a week, and the pH comes out of the tap in the 7.4 range, but my straturm brings the pH down to 6.8,  I am very careful with the temperatures, but perhaps I am causing too much of a temporary swing?

3. Some unknown aggression, but I don't see it.  However these are small areas on the fish body with a single white fungal growth.

4. Something with the manzanita wood and blue petrified wood could be causing an issue?

Thanks,

 

 

[Fish Folk]

I’m not exactly sure if I’m envisioning your set up and situation correctly, but it may be endemic, requiring a major treatment with something like API Fungus Cure. It will turn your water wildly green for awhile. Use exactly as directed.

Here’s a video from my last time dosing for major fungus issues…

Once a fish gets injured, if your water is not very clean, fungus may grow on certain wounds. Typically it results from overfeeding + endemic development.

Use a whole-tank fungus cure, then feed sparingly.

[FredF]

On 11/30/2021 at 9:02 PM, Fish Folk said:

I’m not exactly sure if I’m envisioning your set up and situation correctly, but it may be endemic, requiring a major treatment with something like API Fungus Cure. It will turn your water wildly green for awhile. Use exactly as directed.

Here’s a video from my last time dosing for major fungus issues…

Once a fish gets injured, if your water is not very clean, fungus may grow on certain wounds. Typically it results from overfeeding + endemic development.

Use a whole-tank fungus cure, then feed sparingly.

Sounds like ICH X might work.  Attaching a couple of pictures of my tank.  I’m pretty sure I am not overfeeding, but maybe there is some stressor I am not aware of.

[Fish Folk]

On 11/30/2021 at 9:20 PM, FredF said:

Sounds like ICH X might work.  Attaching a couple of pictures of my tank.  I’m pretty sure I am not overfeeding, but maybe there is some stressor I am not aware of.

Breathtaking beauty! Well done. Great work . . . 

[Colu]

If it's fungal you can treat with ick x as API fungus cure has  acriflavin in it and that can damage live plants if you feeding kanaplex in food you can treat the water column with ick x