Not Enough Oxygen In The Water?

[Karplunk]

Hi, I recently bought 4 neon tetras in my new 5 gallon fish tank. The tank is fully planted and I treated the water with tap water conditioner. I have only a filter installed in the tank (as I heard that internal filters aerate the water as long as it create "ripple" on the water surface).

Yesterday when I thought there was not enough oxygen in the water, I put my filter at its full power and I came back 2 hours later, and 3 of my neon fish died. I put the filter at its lowest power and the remaining fish is still alive right now. However, the survived neon fish like to go close to the filer and ride the wave. Does this mean that there isn't enough oxygen in the water?

The tank temperature is 78F
pH is 6.9

 

[WILDER]

Sounding like your tanks still cycling.
Do you have water stats in ammonia, nitrite, nitrate, and ph.

If the fish are struggling with the current turn filter down to the low setting.

Do you have any other fish in the 5 gal tank.
Even though the neons are small fish they needs at least 10 gals as there shoaling fish.
Also they should be kept in no less than a group of 6.
Neons need mature tanks of 6 months. They shouldn't be used to cycle a tank as there very sensitive to water quality.

 

[Karplunk]

nitrate: 20
nitrite: 0
ammonia: 0
pH: 6.9

I have no other fish in my 5 gallon
How do I know if the fish is "struggling with the current"? My remaining neon tetra is still swimming all over the tank.

 

[WILDER]

As long as the fish are not being blow around the tank by the filter.

What rest kit are you using?
Did you cycle the tank before you added the neons.
How long did you climatise the new fish for?

 

[Karplunk]

As long as the fish are not being blow around the tank by the filter.

What rest kit are you using?
Did you cycle the tank before you added the neons.
How long did you climatise the new fish for?

I use the virbac mardel 5 in 1 Test Strips.
I cycle the tank for about 1 day before I go out and buy the neons.
I climatised the neons for about 30 minutes

 

[WILDER]

Test strip cards are not accurate. Liquid test kits are the best.

You will need to do some research on the nitrogen cycle.

Your water stats are not making sense for a newly set up tank.
I would take a sample of your water to the lfs and ask them to write the reading down for you.
I would really suggest taking the neons back to the store and maybe think about doing a fishless cycle.

Research the fish before you buy for tank size, and adult size of fish.
There not that many fish that can be kept in a 5 gallon tank.



If the filter ripping the water well aeration should be fine.
Fish gasping at surface of tank can be bad water quality, lack of aeration, parasites, toxins, bacterial.