Fin rot or aggression?

[Deadeye]

Have you tested your water?

No

If I did not test my water...

...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

What percentage of water do you change?

21-30%

How frequently do you change your water?

Every two weeks

If I do not change my water...

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

Within two days this happened:
The mbunas have done this to others before, but usually all the fins are destroyed and the fish is unable to really swim and are missing scales. Other than the caudal fin he looks fine.

 

[kno4te]

I’d guess aggression.

 

[The Morning]

Yup have to agree. That looks like he is getting picked on.

 

[Deadeye]

The only thing I can do to limit aggression is just overstocking, right?

 

[Rocksor]

Yes for Africans, no for Central/South Americans

 

[Deadeye]

Would I be best adding a lot of one species or only getting one of each type?
Also, in the past overstocking just resulted in too much bioload (I can just do more water changes to fix that) and them still picking each other off, any suggestions?

 

[Dalfrey86]

Would I be best adding a lot of one species or only getting one of each type?
Also, in the past overstocking just resulted in too much bioload (I can just do more water changes to fix that) and them still picking each other off, any suggestions?

Depends, I run two HOB on all my tanks to support overstock and redundancy in case one fails.
As for the WC, weekly is a must if you overstock if not every 3 days if under filtered.

 

[The Morning]

I find that with mbuna you will be hit and miss depending on each individual fish, overstocked or not. Some species are known for being more aggressive than others but even individual fish can throw a balance out of whack. If you are not going with a same species tank you will have to go with a trial and error method and be prepared to either lose some fish or rehome.

 

[Deadeye]

Update:
They never finished the job, so he was left to be able to heal. His tail is almost back now!