Sudden extreme territorial issue in cichlid tank.

Came home from work today to see a bunched up pile of 10 cichlids in one corner. The big one is keeping them all there. Has it finally had enough of the glass surfing? I've been thinking I should probably re-home it as it does glass surf much of the day. It's the biggest one in the tank. What should I do now.. idk anyone who can take it and the others can't stay how they are. Will they balance the aggression back out naturally?

It has been a LONG time but I used to do a LOT of South American Cichlids including Blue and Yellow Acara, Green Terrors, Jack Dempsey and Convicts all peacefully co-existing in a 50 gallon tank. I have also done this in a 30 Gallon tank. The thing is adding new Cichlids that are mature or adding ones that are not with mature fish already in the tank can be problematic. I got away with it by putting all in the tank when really young. If you add small Cichlids to a tank that already has mature the mature fish are just going to see the small ones as a source of food in most cases.

Have you recently added more smaller fish? If so the larger mature fish MAY be seeing a territorial threat. Well, it could be seeing a territorial threat even if you have not recently added new fish but more likely if you have.

Unless you want to risk the smaller ones being killed I'd get the larger out of the tank.

It has been ~25 years since I've dealt with Cichlids so please, anyone, point out where I may be wrong in my thoughts.

I took in this tank from an older lady whos husband had passed a couple years ago. They've all been living together for years. It seems to have calmed down now a bit. I took out 10% of the water and added 20% to replace and top off again. Thinking maybe the salt was agitating it?.. slowly taking it out with smaller water changes. They're all staying on the other side, but not in such a pile anymore and the big one isn't being as aggressive anymore. Still swimming over to keep them in check almost, but they're not acting as scared and it isn't acting like it trying to decrease the population lol. Not targeting a specific fish, so it's not for any reason but to help it's own comfort. I feed a lot, and they're not losing weight, so it can't be food. I'm thinking it needs more of it's own space honestly.

I've never used salt in a Cichlid tank but have heard about it being done. The first thing I noticed in your last post is that you removed 10% of the water and added 20% to fill. This would mean that the salinity level was high as the tank was initially low by 10%. One must always remember that water evaporates but salt does not.

It's caused by lack of hiding places and the dominant fish wants to breed. He has taken over the tank and says it's his territory and anyone who enters will die or be bashed.

You can try adding a heap of rocks, caves & pvc pipe to give the other fish somewhere to hide. More plants can help but make a wall of plants and rocks so he can't see through them easily. It doesn't have to be solid but just something to obscure his vision.

If worse comes to worse, you might have to remove him, but then the next dominant fish might take over. This is cichlids being cichlids and the main issue when keeping them.

Nice tank, but not nearly enough protection for this group of fish.

Yeah just reiterating what others have said, you need lots of nooks and cranny’s for them to hide. Also what is your feeding routine? What can also calm aggression

I don't usually keep salt in the tank, used it this time from recommendations for the blue ones wounds. I didn't add in the full amount I should cause I was so sketched with it lol, so it wouldn't have been over the necessary amount, but that was a good reminder! Because I didn't think of it when I did add what I did, so If I wouldn't have been scared, I would have added extra. Ty!!!
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As for the decor, I'll work on getting more appropriate things to put in there. I seen and thought about the PVC the other day, so I'll definitely do something with that idea. Ty!
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I feed at least 3 times a day most days, some that sinks, some that floats, and some that floats all around all at once every feeding so there's not as much competition.