Aggressive cardinal fish?

bairdimusprime · Jan 14, 2016

Ok so my larger cardinal fish is very territorial i guess. it killed one my two other cardinals and chases the other cardinal fish around the tank... is this normal behavior? he leaves the clownfish alone though.

thanks

143MPCo · Jan 14, 2016

I have 3, 2 get along without issue, but 1 of the 2 run #3 round the tank soon as he thinks he's too close.
Never had a death in my system from territorial issues but, have read a view thread claiming that it happens.

3dees · Jan 14, 2016

what kind of cardinals? bangaii's will not tolerate each other unless they are a bonded pair. pj's are better in groups.

reefwiser · Jan 14, 2016

I had Three PJ's and the head dog PJ killed the bottom one. Cardinals can be aggressive. Mine now stay and opposite sides of the tank.

bairdimusprime · Jan 14, 2016

3dees said:
what kind of cardinals? bangaii's will not tolerate each other unless they are a bonded pair. pj's are better in groups.

Bangaii's
bought three, now i have two and the big one is pretty darn mean to his companion fish

Lionfish Lair · Jan 14, 2016

I was going to ask if they were Banggais.... Banggaies..... several Banggai.

They're not nice to each other in small aquarium groups.

bairdimusprime · Jan 14, 2016

its a 60 gallon cube, not many fish 2 picasso clowns, 2 Banggais, and a diamond goby that lives under the rocks with his pistol shrimp. i try not to over do it

DeniseAndy · Jan 14, 2016

My threadfins and dot dash got themselves down. I had three threadfins and 2 dot dash left. Although, have not seen one of the threadfin for two weeks now. I think it may be gone. Took 5 years to get to 2 though. I have three for 4 years. They never bother any other fish though. Even each other.

Lionfish Lair · Jan 14, 2016

bairdimusprime said:
its a 60 gallon cube, not many fish 2 picasso clowns, 2 Banggais, and a diamond goby that lives under the rocks with his pistol shrimp. i try not to over do it

I meant not nice to each other in small numbers in most any aquarium.

They're probably not nice to each other in larger numbers either, but the aggression is spread out over a group of individuals, not just a couple.

bairdimusprime · Jan 14, 2016

Thanks @Lionfish Lair sorry i took your post wrong... the joys of reading and not actually speaking with someone...

Lionfish Lair · Jan 14, 2016

Proper grammar would help my cause.

Josh King · Jan 20, 2016

I had 3 small 3/4 inch Banggais . They lasted 1 night.

They could not handle the flow of my tank. Is this common?

Irene · Dec 1, 2017

I keep reading that Bangaii cardinals are great, peaceful community fish. I have two (third one disappeared a while back) along with other community fish, and they have been doing well and growing. Yet, I decided to add two more young bangaiis and all h*** broke loose. The two older fish are following and confronting them and making aggressive ‘shaking’ movements. I had no idea they are so aggressive.
My question is, what are the chances they will get used to each other, if so how long do I give it, or should I just take them back now? Thanks

DeniseAndy · Dec 1, 2017

All cardinals I have owned (blue eye, dot-dash, pj) have always settled themselves to 2 in the end no matter where they started. Seems to be a captivity thing. I have a 210g that they have gone into, so not small tank.

Irene · Dec 1, 2017

Thanks, my tank is much smaller but has lots of hiding places so will keep an eye on them and hope for he best.

uclaray · Dec 1, 2017

Irene said:
I keep reading that Bangaii cardinals are great, peaceful community fish. I have two (third one disappeared a while back) along with other community fish, and they have been doing well and growing. Yet, I decided to add two more young bangaiis and all h*** broke loose. The two older fish are following and confronting them and making aggressive ‘shaking’ movements. I had no idea they are so aggressive.
My question is, what are the chances they will get used to each other, if so how long do I give it, or should I just take them back now? Thanks

The two you have left are now probably a bonded pair, that's why the third one disappeared. Unless you have a very large tank, the pair will probably kill the new ones you put in, so I would just take them back.

Irene · Dec 5, 2017

Just a follow up, I found one of the young fish dead this morning. And can see only two others (there were two original fish and two younger fish added last week), so maybe another one is gone too. The two remaining are at opposite ends of tank. Someone mentioned they work themselves down to two, definitely true in this case. . I am shocked and sad to send these fish to such a fate, and learned a lesson here— be careful introducing this species

Zionas · Sep 11, 2020

After reading this I’ve decided to maybe just stick to one PJ Cardinal if they’re not hermaphrodites and are hard to sex. Not sure if this is the same in the work but is it true that fish even in the wild are often seen together as a defense / conformity mechanism more than liking each other? If that’s the case, I’d say it’s the same for a lot of people.

With humans sometimes a group will really like each other, sometimes humans just stick together for security (a false sense of it if you ask me) but as soon as there’s a social powder keg all hell breaks loose, and we assert dominance over each other in subtle and not so subtle ways in groups.

If anything these fish are just like me. I’m a very chill person as an individual or with another person, when I’m in a group my behavior changes to being a lot less comfortable.

Maybe in the wild, with predators and other threats, some fish choose to stick together for survival purposes. In the aquarium, in a much more confined space and without their natural predators (unless we choose to introduce some), they’ll be much more likely to assert dominance over others for the sake of individual interests.

How’s that different from a lot of human behavior, really?