Aggressive fish - Isolation

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Aquarium Advice Apprentice
Apr 1, 2024
Noosa Heads
Thank you in advance for help!
We have a 200L tank and just purchased 5 juvenile female angel fish, after a 1hr acclimation we added them all to the tank and they were all friends initially… after 1-2hrs in the tank one started being very aggressive to the other angels.
First question… is it normal to be this aggressive so early on?
Second question.. we are going to return the aggressive one tomorrow but overnight can we leave it in a net hanging in the tank? We don’t have a quarantine tank currently (I know we need one)
Thank you again!
Ive tried to keep 4 angels in 200L and it didnt work. They where fine as juveniles, but as they got older it was a problem. If they are juveniles you wont be able to accurately tell male from female, so you really have no idea if they are all female, no matter what the store may have sold them to you as.

All you can do is see how things go. Im going to bet that there is at least 1 male in your group, and what will likely happen is a pair will develop, and the rest will then have to be rehomed.

The other way to go is to have more angels, and just let them establish a hierarchy. Aggression should be more spread out with more fish. Removing the aggressive one might help, or it might just promote the next most aggressive fish to top dog and you have the same problem with a different fish.

@Andy Sager is the angelfish expert here, but my advice would be to either limit numbers to 1 or 2 fish, especially if a pair develops or just accept that angelfish are an aggressive species and let them get on with establishing their heirarchy and see how things work out longer term.

If you wanted to isolate a fish, a bucket or tote box of water and leave the heating on in the room might be better just for an overnight stay.
What you need to understand is that Angelfish by nature are a schooling fish that live in a hierarchy society so no matter how many you get, there will always end up with a "boss" ( a.k.a. #1) and then a #2, #3, and so on. Because of this, you want either a single fish or a number of fish to help spread out the aggression. 2 Angels alone is tough unless they are a mated pair ( which can bring on it's own issues). So what you are seeing is the fish trying to establish their hierarchy and that aggression should subside once they figure out who's which number. Because Angelfish are cichlids, they can get aggressive with each other and there may be rips and tears to the other Angels and sometimes these damages are permanent so be prepared that it CAN happen. With the long history of domestic breeding that was done with Angels, many no longer feel the need to be in schools to feel comfortable so you need to understand that the closer you get to wild caught fish, the more you need to keep them in schools vs alone. If you don't know their heritage, schools are better. (y)

This thread here: Wigglers At Last!!!!! is a long thread about keeping and breeding Angelfish with contributions by hobbyists, home breeders and commercial breeders ( Me :giggle:). Just about everything you need to know about keeping Angels was discussed on this thread. You will gain a lot of knowledge about your fish if you read through the whole thread. (y)

The fact of the matter is that with domestic Angelfish, there has been so much genetic manipulation that you can no longer tell males and females definitively without seeing their breeding tubes. There are males with female characteristics and females with male characteristics now so you won't know for sure until they become sexually mature ( 8 months old +/- ) or they pair off and show their breeding tubes. ( FYI: It is also possible for 2 females to pair off and spawn together so you can't take for granted that just because they spawned together means they are a male and female. :facepalm: )

Regarding you question about isolating the " bully", as Aiken suggested, a bucket with an air stone would be better than a net hanging in the water, especially if it's a large net. Too great a chance the fish will get tangled up in the net and suffocate. :(

Hope all this helps. (y)
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