White patches on Discus

[mark4785]

I have recently noticed that white patches are appearing on 2 of my four Discus. Any help with identifying the disease that they have would be appreciated.

Water quality is at 0 ppm for Ammonia and Nitrite and 20 ppm for Nitrate. pH is 6.5 and water temperature is 29 degrees C.

 

[Colin_T]

poor water quality. do 75% water change and gravel clean substrate every day for next 2 weeks. clean filter if it hasn't been done in last 2 weeks. make sure water quality is perfect. monitor fish over a few weeks and post more pics if it gets worse.

 

[mark4785]

Hi Colin,

It is an aquarium with no substrate and the filter was cleaned 4 days ago. Water quality is perfect as mentioned in the original post.

 

[Byron]

Nitrate at 20 ppm is not indicative of good water quality; it is now accepted that all freshwater fish are negatively impacted by nitrate, and cichlids seem particularly bothered by this level. If this is in your source water, that is one issue, but if nitrate is this high solely from within the tank then you have a water quality issue as Colin noted.

Bare tank substrates are not good. I know discus are frequently subjecteed to this but it does stress them. The important bacteria bed in the substrate goes a long way to healthy fish; the substrate is more important than the filter in this regard. No mention is made of water changes, but they may not be adequate given the nitrates (unless these are largely in the source water of course).

 

[mark4785]

So what is the problem with the fish please?

I can confirm the fish have been healthy in the presence of 20-50 ppm of nitrate over the last 5 years.

 

[Byron]

So what is the problem with the fish please?

I can confirm the fish have been healthy in the presence of 20-50 ppm of nitrate over the last 5 years.

The fish are not healthy in nitrates that high. The fact that they do not die does not mean they are healthy, it means they are struggling and coping. They are stressed, which slowly wears them down, allowing things like whatever this is to occur. As for what this is, I have no idea. My experience with disease is next to nil, and it is not an area I have researched and I will not guess, that would not help you or the fish. I do know what weakens fish, and i do know that stress from any number of factors is the direct cause of 95% of fish disease. So reducing stress goes a long way to keeping fish truly healthy.

Nitrate, like ammonia and nitrite, is poisonous to fish. Unlike ammonia and nitrite, nitrate can usually be somewhat tolerated depending upon the level, the duration, and the species. But in the end, all fish will succumb to nitrate poisoning, whether this be increased susceptibility to disease, or a shorter lifespan, increased aggression, whatever. Most stress (until it becomes chronic) is externally not obvious to us. Neale Monks explained to me that we should think of nitrate as simply slowly weakening the fish until it can no longer deal with "x" and succumbs. And the fact that nitrate in the habitat waters is usually zero or no higher than 1 or 2 ppm should tell us something about how fish will (or won't) cope with it.

 

[mark4785]

I am looking for disease identification to be honest. I don't think nitrate is a problem in the slightest. Nitrate is added purposefully each week as this is a planted aquarium. This has been the case for the last 12 years.

I could go on and on about how my cichlids and koi have bred in water containing nitrates of around 50-60 ppm but my main concern is identifying the disease since i've never seen anything like this before.

 

[mark4785]

The issue, whatever it was, seems to have cleared up of its own accord.