# Distressed cardinal tetras - could it be allelopathy?



## joeinlondon (7 Oct 2008)

Now a little knowledge is a dangerous thing, but I was reading Walstead's book last night and thought that some sort of allelopathy may be affecting my cardinals, as I can't think of what else it might be.

I have noticed in the evening, about two hours before the lights are due to turn off, one of the large ones, or one or both of the two newest (and smallest) additions begin swimming up against the glass, as if trying to get out.  Obviously something is affecting these individuals, and they are unhappy.  At other times normal, fairly placid behaviour is observed, with the usual sparring and chasing.

The tank is 67L, substrate 2-4mm gravel with laterite, 25w powerglo for 8 hours daily, Tetra internal filter at about 400lph.
Water is pure RO, 15L changed a week.
Additives: easycarbo @ 2ml/day and TPN+ @ 2ml/day
Moderate planting.

Ammonia and nitrite consistenly zero, nitrate 10ppm, pH stable at 7.

I am also having staghorn algae issues (Type II on James' article [overfeeding]), and last night a bit of surface scum, but my main concern is that something is bothering the tetras.

*Are my water changes too small, and the resultant build-up what is affecting them?*  Before I switched to TPN+ I was using Colombo Flora Grow, and probably overdosed it, so perhaps it might be some residual traces of copper which I have read about on this forum - I don't know.  The shrimp in the tank seem okay, if a little shy and unindustrious.

Any input would be much appreciated.

Thanks as ever
Joe


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## aaronnorth (7 Oct 2008)

if you have surface scum, it could be affecting the gaseous exchange and the fish may suffering from oxygen defficiency, do you inkject CO2?


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## Carphunter57 (7 Oct 2008)

I would have said that they are just sparring with their own reflections. Some of my fish do it on occasions and I have never considered that there was any problems.


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## vauxhallmark (7 Oct 2008)

Unless you've got a dark background outside the glass, the fish don't see any reflections in the glass. (You know what I'm going to suggest if you don't believe me!). We don't see reflections on the pane parallel to the one we're looking through, only on the ones perpendicular to it (ie, if you look in the front of the tank you can see out through the back pane, but the sides appear like mirrors (I think this is why Amano puts the filter hoses etc. on the side of the tank), but if you look in through a side pane, you can see out of the other side, but the front and back panes will appear like mirrors).

From inside the tank, this effect does not occur.

However I agree with you, fish chasing up and down the glass a bit isn't always a bad thing. Doesn't look good though! I always spend a bit of time watching fish I've never kept before in fish shops, as I don't like this behaviour, or really fast skittish swimming. Cardinals actually don't do this too often.

Good luck with the cardinals, Joe, hope they settle down.

Mark


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## Carphunter57 (7 Oct 2008)

[color=#0000FF:3w06nx7r]vauxhallmark said:
			
		

> Unless you've got a dark background outside the glass, the fish don't see any reflections in the glass. (You know what I'm going to suggest if you don't believe me!). We don't see reflections on the pane parallel to the one we're looking through, only on the ones perpendicular to it (ie, if you look in the front of the tank you can see out through the back pane, but the sides appear like mirrors (I think this is why Amano puts the filter hoses etc. on the side of the tank), but if you look in through a side pane, you can see out of the other side, but the front and back panes will appear like mirrors[/color]).



Agreed. But. if the light levels are higher in the tank than in the room then surely you are going to get a mirror like effect within the tank.

Certainly in the evenings my tank is the brightest thing in the room (yes it's probably a lot brighter than me   ) so I would have thought the potential for the fish to see their own reflections at times is pretty high.

I spend a fair bit of time behind glass (I drive somewhere in the region of 40,000 miles per annum) and a certain times of the day I can see my reflection in the glass.


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## joeinlondon (8 Oct 2008)

> if you have surface scum, it could be affecting the gaseous exchange and the fish may suffering from oxygen defficiency, do you inkject CO2?



Aaron - I'm just using Easycarbo at the moment but going to install a proper pressurized kit on Friday.  Before I was using a crude aerosol injector and that did cause a lot of surface scum - from what I've read I think the fluctuations inherent in the design of the 'injector' were battering the plants, and making them 'release sugars', as Clive would say.  No surface scum yesterday though...

Mark & Hunter57 - your suggestions about seeing their own reflections are interesting, and I wish it were the case - but I 'know' these fish (at least the older one), and in the previous incarnation of this tank the lights were on for hours into the night, and there was never any sign of this 'swimming' behaviour.  And you can tell when a fish is distressed - I think these fish _are_ distressed, and want to get away from something, and they don't care which pane of glass they swim against.

My current theory is that now that the plants have grown a bit, they use all the Easycarbo in the first six hours, then start 'releasing sugars' because suddenly it is not available to them, which irritates some of the tetras.  What do you think?


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## vauxhallmark (8 Oct 2008)

Carphunter57 said:
			
		

> Agreed. But. if the light levels are higher in the tank than in the room then surely you are going to get a mirror like effect within the tank.
> 
> Certainly in the evenings my tank is the brightest thing in the room (yes it's probably a lot brighter than me   ) so I would have thought the potential for the fish to see their own reflections at times is pretty high.
> 
> I spend a fair bit of time behind glass (I drive somewhere in the region of 40,000 miles per annum) and a certain times of the day I can see my reflection in the glass.



I bow to you. If it's darker outside the tank, of course they'll see reflections - d'oh! Why didn't I think of that?

M


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