My Neon Tetras are fighting

Hello, I noticed today that my neon tetras started fighting out of nowhere. In the tank I keep 8 neon tetras, 5 harlequin rasboras, 4 Cory catfish, a molly, and a platy. None of the other fish are fighting besides the neon tetras. My water parameters are normal, 0ppm ammonia, 0ppm nitrite, ~30ppm nitrate. The ph stays at around 7.8-8.0. The tank is fully cycled and I’ve had the fish for around 10 months now. I can’t think of anything that would be causing the tetra to fight. Is there anything I could do about it? Thanks

 

Tetras bicker. Absolutely normal for these little piranha. How big is the tank? Some structure, like twigs and branches might be helpful.

Nitrate is a bit hight (up the waterchanges) pH is as well for most of your fish, but you can't go down because of the livebearers.

 

The Neons fighting is a good thing. It indicates healthy robust fish. As long as the fighting isn't causing injury, no worries.
Chances are the sudden aggression is mating behavior.

 

Chances are the sudden aggression is mating behavior.

Not in these parameters. Not neon tetras. They might not need it as low as cardinals, but it's highly unlikely with a pH of 8.

 

That's true. I didn't consider the elevated PH.

 

Tetras bicker. Absolutely normal for these little piranha. How big is the tank? Some structure, like twigs and branches might be helpful.

Nitrate is a bit hight (up the waterchanges) pH is as well for most of your fish, but you can't go down because of the livebearers.

The tank is a 20 gallon tall. My tank produces about 20ppm nitrate per week. What should I try to get the nitrate down to when I do my water changes?

 

What should I try to get the nitrate down to when I do my water changes?

10-20mg/l are a good level, rather towards 10.

 

You know the phrase "cool it".

When my Neons were fighting I lowered the temp gradually over a week from 78 to 72F and they fought no more. I've heard that this is a common temperature they are found at in the wild, though the wild temperature fluctuates.