Shell dweller suddenly sick

[Angelfish1]

Male1 used to live in a 36 gallon with 2 females and 7-8 fry. I added a new male (male2) into the tank and male2 was getting beat up at first but on New Years male2 finally held up his own territory and became an outcast. Yesterday I came home from school to see the male1 (dominant male) getting beat up by male2 and not fighting back. He was getting pushed around like male2 was previously. Now male1 isn’t looking in good condition. What caused this sudden change (disease/age/etc?)?? I’ve tried multiple times to add male2 to the tank but the male1 has always pushed him into the corner, until this time when I rearranged the tank. It’s very unusual that male2 suddenly became the dominant one after being the weaker one for so long.
I separated the male1 into my 75 gallon community tank for now. I’m not sure what’s wrong with him so I’m unable to treat him.
Previous dominant male (male2):

 

[A201]

It's not unusual for a Cichlid hierarchy to change up. Doesn't necessarily mean the once dominant male is sick.

 

[MacZ]

It's not unusual for a Cichlid hierarchy to change up. Doesn't necessarily mean the once dominant male is sick.

Not from the start, but it can become a problem when they keep being chased.

I separated the male1 into my 75 gallon community tank for now.

What else is in there? Do the water parameters fit for Tanganyikans?

With fitting structure in the shellie tank you should actually be able to split the colony. The separation might have made this impossible though.

 

[Angelfish1]

Not from the start, but it can become a problem when they keep being chased.


What else is in there? Do the water parameters fit for Tanganyikans?

With fitting structure in the shellie tank you should actually be able to split the colony. The separation might have made this impossible though.

I had the colony split originally in 2 different tanks but the Multies were taking up a lot of territory so I merged the colonies into the 36 gallon. There’s 2 angelfish, 8 glofish tetra, a kuhli loach, and some algae eaters in there. The pH is 7.8 in both tanks but I’m trying to raise the pH for them by adding dead coral in the 36 because the water is too soft for them. One multi will be fine temporarily in the 75 (that’s where male2 was previously) but it isn’t what I wanted as the 75 gallon is kind of serving as a holding tank for the male and he doesn’t fit in with the tropical fish. I was hopeful when the male hierarchy finally worked out the other day that they’d finally be fine all together but the male hierarchy is in shambles again. I think if male2 is not sick, I’ll probably let him rest a bit in the 75 and rearrange the 36 so that I can try to put both males in the same tank again. Do you know how I could successfully split the colony up in the same tank?

 

[MacZ]

I think if male2 is not sick, I’ll probably let him rest a bit in the 75 and rearrange the 36 so that I can try to put both males in the same tank again.

That would definitely be my advice also.

Do you know how I could successfully split the colony up in the same tank?

I hate to say it as a German, but... build a wall. Take a handful of rocks and separate the tank in a height of 0-15cm above substrate level completely. There should be as little chances to glimpse through as possible.