Normal for Neons to swim downwards?

Big Fate

Yes, only the neons do it.

Ammonia: 0
Nitrate: 40
Nitrite: 0
GH: 300
Chlorine: 0
KH: 180
PH: 6.5 - 6.8

Olympia

Hmm. Your water is 17dH. I know neons have adapted to some degree but it may be too hard for them.
My theory: Soft water fish come from places with low mineral concentrations. When placed in hard water, it can take a huge toll on the kidneys, which filter minerals. Neon Tetra in particular have been studied and their kidneys take quite a bit of damage in harder water. The kidneys aren't evolved to deal with so much mineral, so they swell. And, in fish swollen organs means floaty bodies.
This problem will probably end up being chronic, you can try softening the water if that'd be possible, but usually fish with these issues don't fare too well. The cherry barbs(?) are more tolerant and that's why I think they are unaffected.

Nitrates are a bit high as well.
I know there could be a number of other causes, but to me it seems most plausible.
Posted via Mobile Device

Big Fate

You could be right.. The water here is really hard. I was actually thinking of switching over to RO water or 50-50.

Nitrates are a bit high because I just dosed KNO3 today in the morning.. it should drop down a bit by tommro after the plants consume it

Termato

Is this tap water you are using?

Where did you get the neons? Locally?

I am thinking that if you got them locally and they use tap water without treating it and you use tap water then there should not be a problem with that.

I do agree with Olympia that the hardness could be the problem. You should try quarantining all the neons you have.

Byron

The video worked for me today, so now I've seen it. I don't see a problem with the neons, except they are fighting too strong a current.

Can you somehow reduce the flow into the tank from the filter? These fish occur in very quiet water, and fighting a current (which is what they are doing with their head down...just as we face strong winds by bending forward) will wear them out.

Byron.

Termato

To help slow down the flow of water, more floating plants will help.

You could also jam a small bit of plants or cloth or something into the output of the filter.

Big Fate

I could easily slow the flow down with the quick disconnect valves on the canister. Only problem with your theory is the strong flow is on the opposite side they are swimming downwards at.

They've also been swimming like that before I even had a canister and just had a HOB with alot less flow

Termato

How did you get your Riccia to stay together like that?

You can also try filling the tank a bit more. That could help the flow.

The neons in the video are going the opposite way the riccia is spinning which looks like is against the current. I don't see what you mean "strong flow is on the opposite side they are swimming downwards at"

In the video the water flow does not appear to be too strong because the plants are not moving that much.

Has this problem only happened to the neon tetras?

Byron

Well, I just watched the video again, as I want to be certain, and i still say there is too much water current. It would be easier to see if you held the camera steady in one spot so we could see the entire tank, as the camera movement does conflict with what I'm seeing in the way of plant and water movement, but it is pretty clear to me that there is a current from right to left near the front: first, the floating ring of plants is doing a spiral in this direction (clockwise from above it would be), and the neons are bucking the current when they swim from left to right. I also see plants swaying down in the tank, and that means far too much movement in the water column. Except right at the filter return, plants should not be moving at all. This then creates the water flow these fish were designed by nature to deal with. Half the year they live in flooded forest, which has basically no water flow at all, aside from thermal currents.

Termato

How would you reduce water current Byron?