One Unsociable Tetra

So it's been a fortnight and my 9 Congo tetras have settled in well, all look lovely and are swimming freely across the tank now except for one, she's the biggest female of four, and she looks fit and healthy, she's very vain and spends lot of time admiring herself in the reflective glass, but boy is she mardy, if anyone comes too close she chases them off, and although she will swim near them, isn't joining in the fun, is this normal fishy behaviour i wonder?

Hee hee!!

She sounds like she's found her territory and is defending it vigilantly!!!!  I think as long as she is healthy and happy, eating well and not overly withdrawn she is probably behaving quite normally. I don't know if tetras get territorial if they are full of eggs? I'm sure someone will know!! 

 Just keep an eye on things for now!

FC76

Most shoaling fish have a pecking order of dominance and she is obviously at the top for now. When some of the boys get bigger, since male congo tetras do get bigger than females, this may change.

Hi,

I've had my x-ray tetras for almost 3 months now, and I notice that behaviour (including pecking order, pairing-off which incidentally is generally size-pairing rather than male/female pairs, nocturnal habits, distancing from the shoal which originally was one but now occasionally two) has changed over this time.

The introduction of extra plants at the rear of the tank caused a change in behaviour - moving the fish towards the front of the tank, and one of the two larger fish decided to occupy the entire 'free-swimming' area; any fish that approaches this area gets chased away by her for much (but not all) of the day, while another seems to spend his time staring at the glass/reflection.  No-one in the tank seems perturbed by this, though, and they just swim off elsewhere to play, while the one on his own seems to be keeping an observational eye on everything in the reflection rather than admiring himself; I'm fairly certain that a re-arrangement of decor might change the social structure and habits again.

In a nutshell, therefore, I think it's a matter of "watch this space" re your fish's behaviour...