My Cardinal Tetras

[SouthernCross]

Hi everyone

9 days ago I got a new group of 10 cardinal tetras for my community tank. Acclimatised them slowly, they had hardly any red (from being stressed in the bag I assume) when I added them but they've since quickly coloured up nicely. Which is good, I had expected to maybe lose a few, but maybe I'm lucky *touch wood*. One had the lower part of its tail missing when I looked closely but other than that they looked good. Is it true that their 'redness' is a good indicator of their health/water quality?

Anyway, first few days they all hung out together and schooled well in the front (looked fantastic! ) but now they've settled in they've spread out a lot and are mostly hanging out in the plants at the back (out of the light I think). In the last two days I've noticed sometimes they're chasing each other and looking like they're trying to nip at each other. Is this normal? Should I be worried about this aggression, will they kill each other??? I've been doing a headcount every morning. Or is this some kind of breeding behaviour? I thought schooling fish all got along well with each other...

I wish they'd school again but I guess it just means they're not frightened or stressed. Their tankmates are cories, platies, and a large pearl gourami so I guess they have no reason to be feeling threatened.

Anyway, should I be worried about their behaviour? Is there anything I should do?

 

[Lateral Line]

You are correct. Schooling is a defensive behaviour. When first introduced, the stress of moving causes insecurity and they school up. Once they have calmed down, they do their own thing. What you are now seeing is also very typical. Once the new group have calmed down, they will joust about amongst themselves to establish the "pecking order" or social hierarchy in the new group. Such sparring typically last from a few days to a week or more, but rarely does any harm.

 

[Griz]

Lateral Line has covered it well. I've seen the same thing with my cardinals. I originally had 6 and they did exactly the same thing as yours. No harm was done to any of them. 6 months or so later I added 10 more and they went through the same process of sorting out the pecking order. Again, no casualties. Once in a while I still see skirmishes but I'm not sure if this is dominance or courtship behaviour. Sounds like yours are settling in normally.

 

[SouthernCross]

Ahh that's a relief.

Thanks guys

 

[fishlette]

yeah i agree with everyone. when i first bring tetras home (i keep rummy nose, neons, bloodfins, pristellas, lamp eyes, glowlight and black neons) they always hang out together for the first few days and then they seem to settle in to their normal behaviour. in every group there must be an alpha and they will sort that out between theirselves