Interesting Cardinal Tetra Behaviour

[Brette]

I have a small aquarium at work that I stocked with 4 cardinals. I've never had any luck with them in previous tanks, mostly because I think the other fish were eating them and I was too stupid to have predicted that. ("they won't eat each, my fish aren't canibals).

So 3 months later, my little cardinals appear happy and healthy and have really come out of their shells, to the point where they're becoming terratorial. I was shocked. I have never seen this behaviour before with cardinals. My guess is that perhaps the ones I've had in the past in community tanks have been too busy trying to avoid the jaws of a large angelfish to exhibit any natural cardinal tendencies.

Has anyone else seen this?

 

[gpgscott]

All fish are territorial and aggressive to some extent. Yes when in a close community environment the behavior of one type may be influenced (supressed) by another more naturally aggressive type but when you have a group of same same you see some individual 'personalities. Also be aware that stress will make fish aggressesive, poor water quality etc.. and if you have one getting feeble or with a sickness it will be a target for the rest. I have a semi aggressive community and whenever I see someone trying to stake out a piece of the tank and defend it I move things around. Scott

 

[Sibelius]

A larger group will spread out aggresion due to natural shoaling behaviour. Cardinals like to be in groups of at least 6.

 

[mikster]

My cardinals did that not long after i got them, they dont do it as much now but if one strays in the wrong area of the tank one of the others will chase it off sometimes.

 

[NEONCORY]

My cardinals did that not long after i got them, they dont do it as much now but if one strays in the wrong area of the tank one of the others will chase it off sometimes.

Although I never kept Cardinals I have been kept Neons for long time. And they do same thing. They become relaxed enough, they will claim their own spot and if someone try to invade the spot, he/she will try to chace it away. It also happen when the male try to visit the female and the female is not ready to mate. She will chase him away. So it sometime the sex courtship and sometime it just plain the staking the territory. Each fish need their own space when they are not worrying about their own survival.
That is why most of the time, so called "schooling fish" school when there are some kind of danger threatning. Schooling behaviour is the defence mechnism.

 

[millym]

hi
our cardinals & rummy nose tetras are exactly the same, they spend all day chasing eachother away from their own little patch & at lights out gather together again in a shoal

 

[Gazoo]

I have a small aquarium at work that I stocked with 4 cardinals. I've never had any luck with them in previous tanks, mostly because I think the other fish were eating them and I was too stupid to have predicted that.

What size tank are your cardinals in at work? Are there any other fish in the tank?