Angelfish aggression towards livebearers

I have an adult male black Angelfish in a 35-gallon live planted aquarium. Additionally I have 5 assorted livebearers (Molly, platy, guppy) and 2 corydoras. Lately the angelfish has been very aggressive towards the other livebearers. Chasing them around, clearly causing them stress as they spend most of the day sitting at the top of the tank. Everything else I’ve researched shows that livebearers and angelfish should be able to cohabitate. Any reason why this could be happening?

Other specs
-pH around 7.5
-Hardness is pretty high (KH 180-240, GH 120ish).
-Nitrates and Nitrites always at 0
-Weekly water changed at about 15%
-My filter is a little strong for the tank (it’s for a 50 gallon). I was given the tank as a gift and told it was a 55 gallon. I bought the filter before realizing it was actually a 35 gallon
-12 hours of artificial light per day plus a little sun
-78° heater
-No power head
- driftwood and live plants for structure

 

They can cohabitate. But angels "can" (so, it doesn't have to) become territorial.

 

Each angelfish has its own personality. In my aquarium I have 5 angelfish aswell as a platy, ottos, Cory, rainbow shark, gourami. Unless they are breeding , my angels don’t really go out of their way to make anyone particularly miserable. I had the opposite problem where a platy was constantly fin nipping and chasing my angels around! Unfortunately sometimes fish who are “supposed” to be compatible don’t have compatible personalities. I have 1 platy left and she’s great and never has fin nipped my angels.
For your angel, it might be best to remove him if it’s causing that much disruption to all the rest of the aquarium, or use a divider.

 

Although angelfish have a different body shape than other cichlids, they are still part of that same family. Nearly all cichlids can be territorial, some more so than others. I have not tried to keep angelfish in many years as I have had a number who used to peck the eyes out of other fish. Their pointed mouths are ideal for that type of destruction.

Another thing is that you have a variety of different livebearers in the tank. That allows the angelfish to target an individual fish. If you had a group of a single species of livebearer, then the angelfish would have a more difficult time targeting a single fish.

If the other fish were added to the aquarium long before the angelfish and if there is plenty of vegetation and other places for the livebearers to reside, then you might be successful in adding angelfish. But then, you might not. Cichlids tend to have individual personalities and some individuals are more territorial or even aggressive than others. However, it is those individual personalities that make cichlids some of the more interesting inhabitants of aquariums. They often interact with their keepers in a way that most shoaling fish do not.

 

Interesting…….my single adult Koi Angel is in my 75g tank w many Platys, two DGs, and a group of Corys. My Angel generally gets along just fine, but will occasionally, in a half hearted effort, chase a few Platys. As soon as he chases one, there are 4-6 more Platys in the vicinity. He has largely abandoned most chasing as he’s realized, I think, that it’s futile to do so.…..one of him likely getting tired vs two dozen Platys. I’ve never seen him connect with or hurt any fish in the tank……he’s just reminding them who’s the big man.

 

Mine got along with its tankmates for four months, then killed two of them.