Angel's not eating

[Kari Anne]

Hello,

I am new to this site so please forgive me if creating a new discussion was not the way to go.

I have a 55gal tank containing 4 angels, 4 tetras, 1 pleco, and 1 Bichir fish.

My parameters are as follows:

pH: 6.9
High range pH: 7.4
ammonia: 0ppm
Nitrite: 0ppm
Nitrate: 40ppm

temperature: 79 degrees F

The past four days all four of my angels will not eat, however the rest of the fish seem completely normal. all the fish look healthy, no signs of illness as of yet.

My angels paired off a coupled years ago (2 blue angels male and female, and 2 black angels male and female) and I've noticed that the blues have become very territorial over the back left corner of the tank, however, I don't see any signs of eggs anywhere. This doesn't explain why the black angels are acting off, so I'm a bit perplexed.

Has anyone experienced this peculiar behavior? Does anyone have any advice?

thanks!

-Kari Anne