African Butterfly Fish (both not eating)

[Texas1203]

Have you tested your water?

Yes

If I did not test my water...

1. ...I recognize that I will likely be asked to do a test, and that water tests are critical for solving freshwater health problems.

Do you do water changes?

Yes

If I do not change my water...

1. ...I recognize that I will likely be recommended to do a water change, and water changes are critical for preventing future freshwater health problems.

I bought my first Butterfly fish in June or July of 2021. She was active and ate crickets and cruised around whenever I opened the lid. About 2 months later I purchased a male butterfly fish. He was a bit of a bully to my other butterfly but he ate and was a bit aggressive when food was involved. The male stopped eating first, and at times I thought he was dying because I found him in the plants near the bottom (there is floating plants for him to hang out in). Then my female stopped eating. It’s been almost two weeks and I think the male may have eaten one cricket and the female a few pellets. I am concerned because they have stopped eating. Other than the lack of interest in food, they seem fine. No visible diseases or ripped fins. They are both at the top of the tank and even hang out right next to each other sometimes. Should I be concerned they aren’t eating?

Ammonia 0 Nitrite 0 Nitrate 10-20
W/C every Monday 30%

 

[Deadeye]

Any new additions to the tank or changes to the water or scape?
White stringy poo?

 

[Texas1203]

I have added one fish about 3 weeks ago, an elephant nose fish (which is supposed to be a very delicate fish, so water parameters are great or he would be having problems). I have also have been experiencing some black beard algae so every water change I am taking one or two items out and cleaning in hydrogen peroxide and putting back in (but like I said Im doing it slowly as to not mess with beneficial bacteria). I looked at them really good yesterday and they appear to have a few shiny scales, but it looks normal. I will get pics and post them later… I’m just concerned because they used to be real active at feeding time, now crickets will literally be walking on top of them and they don’t go for it. Only one of the butterfly fish will eat pellets. I do feed everyone blood worms (frozen) and either mysis shrimp or freshwater frenzy or flake food or bug bites.