I have a 20 gallon tank that has had very few deaths (just two neons) since I started it up a year ago. Something I can't figure out is why the gouramis I have added die. I added two soon after I got the aquarium and they only lasted a month or so. I added two more about a month ago and they didn't even last two weeks.
I tested the water regular each time, and there was no sign of any toxins. One thing I did notice was a slight change in pH, but I could barely tell; at most it was a .2 change over two days and I think it was less than that. Is that enough to kill a gourami? I understood that neons were a lot more fragile, but they are fine.
I also have a lot of plants in the aquarium, if that makes a difference. Thanks!