Why not enough dissolved O2?

[Just Renee]

I started a 3 gallon Walstad type little tank with potting soil at the bottom, lots of plants, etc.  Everything is going ok, plants seem to be doing well and the two Endlers I put in the other day seem to be doing ok except they keep acting like there is no oxygen in the water until I turn on the airstone.  I thought that with enough plants, there would be enough dissolved O2 for fish?  I ended up having to add these endlers earlier than planned because I found mosquito larva in the tank (UGH! SO GROSS!  HATE SO MUCH) that needed to be addressed immediately or else my husband was going to divorce me.  Unfortunately, that means I'm doing a fish in cycle, which I'm managing with my ammonia and nitrite binding water conditioner and water changes.  Could the messed up parameters be messing with the dissolved O2 or do I not have enough plants to keep the water oxygenated or... something else?

I'm fine to leave the airstone on if they need it, but I really wanted this quiet, no flow Walstad little thing so if I can figure out how to get it all to work without the airstone, that would be great.

[Odd Duck]

Any significant amounts of ammonia could burn gills and make them gasp for breath.  I would probably leave on the airstone until your tank is settled, then see how they do once there’s no ammonia/nitrite/nitrate issues.  They should be fine after that’s resolved.

[Patrick_G]

What temperature are you running? A lower temp will allow more dissolved oxygen. 

[Streetwise]

@Just Renee, do you have a photo to share?

[Just Renee]

[Just Renee]

That pic is before I realized I needed to add the air stone. The first endler ended up at the top, gasping, after about an hour. Once I started the airstone he was fine and swimming around.