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I currently have a 30 litre tank and would like to know how many Cardinal Tetras I can put in before it becomes "overstocked"?

Any advise?

In a tank that size, with just cardinals, you could probably safely keep as many as ten tetras. This might sound like a little much to some, but I think that you could swing it. Tetras produce very little waste, and they do not take up much space either. Besides, schooling tetras like these will always benefit from being kept in good-sized groups, so the more the merrier. The benefits of keeping more tetras outweigh the risks of the bioload being overtasked.

Sorry if I seem a little long-winded, but I'm just trying to explain myself.

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And when he gets to Heaven, to Saint Peter he will tell: "One more Marine reporting, Sir! I've served my time in Hell."

[font color="#000080"]yeah 10 is a good number, having 10 cardinals in there would look real nice.

30 litres converts to about 8 US gallons.

If that is the only fish you would like to put in there, I'd say you could easily get away with 8-10. Like Nick said, small tetras add very little to the bio load. 8 one-inch tetras would not produce nearly as much waste as 1 eight-inch oscar. :%)

That will be a very pretty school. *visualizes tank* Make sure to give 'em some plants.

G/L and HTH

~FF~

-Formerly known as the Ferretfish

uh, no. 8-10 is waaaay too much for an 8 gallon. Keep in mind that these guys get to about 1.5-2", depending on who you talk to. Tip to tail, they are longer than the tank! I'd go with no more than five, as the smaller the tank gets, the more nippy and boisterous the tetras get (ESPECIALLY towards one another).

Cardinal tetras are very peaceful though, especially when they are compared with other tetras. There is very little nipping at all with these fish.

Though they would take up quite a bit of space in a small tank like that, it doesn't matter much. The amount of waste contributed to the bioload is a more important factor, and fish such as cardinal tetras school tightly and don't take up as much space as one might think. I still say about ten would be okay.

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And when he gets to Heaven, to Saint Peter he will tell: "One more Marine reporting, Sir! I've served my time in Hell."

I don't know if you've kept these fish before, but I can tell you that there is a LOT of chasing action going on amongst cardinals once they get settled in, and are very lively. Though they may be peaceful to other fish, they re not in the best of standings amongst one another. As with most schooling fish, they won't school if they feel comfortable. They roam all strata of the tank looking for food as individuals or pairs, and with ten in an 8 gallon, that's way OS. Furthermore, at the rate of water passing accross their gills, they are releasing ammonia into the water---ten tetras will still foul the water up quite a bit.

I own cardinal tetras and have absolutely no problems with them chasing or nipping. I have 7 and they like to losely school, it just seems to be the way they are in small-ish numbers. 8-10 cardinals would be pretty in an 8 gallon

Oh? And how large is your tank? I've had cardinals for lord knows how long--best estimate would be 6 or so years---they were the first fish in my original 20 gallon. They didn't really chase one another at about one fish per two gallons. As I began adding more fish, they began to give chase to one another. Later, I had cardinals in a 75 gallon, and they did a bit of nipping here and there, but nothing serious. Recently, I set up a ten gallon with 7 cardinals from my newer twenty. They squabble like mad. And this is just with 3 adults and 4 fry I found swimming in my 20 gal. Once they all hit 2", I'm in for some bad times. Though it's not chasing to the point of aggression, 8-10 cardinals are much better off in a twenty. However, I recently got rid of my twenty, so it's either the 10 or the discus/angel tank, and IMO, the fry won't stand a chance in there.

Last edited by Cup_of_Lifenoodles at 03-Nov-2004 20:15

Last edited by Cup_of_Lifenoodles at 03-Nov-2004 20:16

Let's limit this to a friendly discussion, and not have things get ugly.
Most of us agree that eight to ten cardinals will work, but there is the chance that it will not. This is evidenced by the debate that we're having. See what works for you. Try six tetras first, and see how that goes. Observe the behavior of the fish, and watch for signs of fighting or overcrowding. If you think you can add more, do so. Otherwise, six would be a good number.

EDIT: Not a problem, I just want to make sure that everyone respects each other's opinions, and doesn't cause trouble.

Last edited by sirbooks at 04-Nov-2004 14:53

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And when he gets to Heaven, to Saint Peter he will tell: "One more Marine reporting, Sir! I've served my time in Hell."

Sorry, I didn't mean to sound hostile.

I've had Cardinals for around 9 years. I haven't noticed mine become especially stroppy or nippy, even though they live in a 'busy' aquarium with 9 Pandas, 7 Otocinclus, and a brace of Lemons and Beckford's Pencils. However, males can, in my experience, become boisterous when "spring is in the air" so to speak I've also had one specimen (I think this was a male, judging by its behaviour) that took up "cave dwelling" in my bogwood boot for a while - it seemed to be trying to entice a female to join it, presumably because in the wild, Cardinals spawn in waters covered by rainforest canopy and shut off from more than 90% of the available daylight. I guess the old instinct made it look for a dark place

Plan the decor carefully, and you might avoid your Cardinals being too fractious. The other alternative is to give them a larger, peaceful, non-threatening in life companion that fools them into thinking there's a potential predator lurking around - in which case they shoal tightly and divert their attention to looking over their shoulders at the big companion



Panda Catfish fan and keeper/breeder since Christmas 2002

Once the newly added specimen is no longer seen as potentially dangerous, they start to swim off again, as I've experienced before.

I think about 6 would be definitely ok. I reckon you could get away with about 9 0r 10 at the most, probobly 8 would be a good idea because you don't want to overstock.