Fishy tales: More myths from the aquarist trade

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seangee

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Commercially farmed fish are more tolerant of different water conditions because they have adapted over a number of generations.

My LFS has exactly the same water supply as me so the fish will be fine

We have all seen these posts on our very own forum...
Today I went into my LFS and on a whim I asked if they had any wild caught cardinal tetras. I had been speaking to the "manager" for a while so he had already sussed that I knew a bit about fish. This is a reputable UK chain that is an aquatic specialist.

LFS bloke: "Oh yes, come this way. These arrived direct from Brazil 10 days ago".
Me: "Wait a minute, this is the hard water section, shouldn't they be in the soft water section?"
LFS Bloke: "Yes that's where we put them when they arrive but we have to harden them up to deal with the local water innit? Once they are ready for sale we move them into this side"


Our local water supply is at 16dGH. The Negro is at 0dGH. I have no idea how long it takes for them to arrive in the fish store after being removed from the river, but I would be very surprised if it was a month. So in less than one month wild softwater fish have magically been turned into hardy fish suitable for water that you can walk on :mad::mad:
 
Myths indeed. First, fish take weeks if not months to acclimate just to subtle minor changes. This is why many experienced sources will tell you not to bother acclimating beyond temperature. But on the positive side, if the water chemistry is not too opposite, the fish usually manage if they are given everything else they "expect" to avoid additional stress. But before someone jumps in, I am talking minor differences between the terrible store tank water and the hopefully near-pristine conditions of your home tank water. We are not talking about hard vs soft extremes.

What the store employee stated is pure fiction, ask any ichthyologist or biologist who knows fish.

A second point to keep in mind is, just how long these "hardened up" cardinals live in the home aquarium? It is common for aquarists to be replacing cardinals every couple or few years. Yet in very soft water they can live over a decade, as the late characid authority Dr. Jacques Gery wrote. Why? Hypothetical question, as we've discussed this many times, but it is a question you might pose to this employee and see how he responds.
 
A second point to keep in mind is, just how long these "hardened up" cardinals live in the home aquarium? It is common for aquarists to be replacing cardinals every couple or few years.
I was one of those who believed cardinals only lived a year or 2. My current shoal are all over 2 years old but in the last year I have lost approx 25% of these due to "old age". These are all "hardened" and when I bought them were kept in very hard water. As I have mentioned elsewhere I have systematically reduced my hardness over the last year or so but it is really only in the last few months that they have been in truly soft water. (By contrast I have lost no glowlights which is the other tetra species I keep). As mentioned elsewhere I am considering trying to breed with these to get the numbers back up - I was hoping to to short circuit the process if I could find some stock that wasn't already hardened damaged. I am pretty confident I will be able to breed the glowlights (they are already spawning in the community tank) but suspect the cardinals won't be nearly as easy.

but it is a question you might pose to this employee and see how he responds.
To be honest I am not sure I have the energy :no:
 
Something else occurred to me just now as I read your latest post. In post #1 you mentioned the cardinals coming from Brazil...is that the case? Because the Brazilian form of this species Paracheirodon axelrodi is, in my view, a much more striking (in my view) cardinal than the Columbian fish. I have only once been able to find Brazilian cardinals where I am.

Now that your curiosity is aroused, I'll explain by citing an excerpt from a profile I wrote on this species some years back.

Two forms of the cardinal tetra are known, one from the Rio Negro basin [the "Brazilian" form] and one from the upper Rio Orinoco basin in Columbia. In the late 1990's, Dr. Jacques Gery suggested that they might differ morphologically, and be distinct species, sub-species or variants; more recent studies are suggesting the latter. They are outwardly recognizable in three ways. On the Columbian form, the neon line ends at the adipose fin, the red colouration does not extend as far under the belly so there is slightly more white, and the fish is chunkier in general build. By contrast, the neon line on the Brazilian form extends below the adipose fin and is straighter in appearance, the red extends slightly further down on the belly, and the fish is more slender and thus appears longer than the Columbian form.

SF also has this info: Weitzman and Fink (1983) observed differences in the number of branched pectoral-fin rays, branched anal-fin rays, predorsal scales, and ventral-limb gill rakers between Rio Negro and Río Orinoco populations whilst also noting that no conclusions could be drawn due to the need for more extensive collections and sample sizes.

The cardinal tetra shares a very similar appearance with three other distinct species, all commonly referred to as "neons" because of the blue/green lateral line. Three of these, the neon tetra [Paracheirodon innesi], cardinal tetra [P. axelrodi] and false or green neon tetra [P. simulans], are available in the hobby; the fourth species was discovered by Heiko Bleher in 2006 and at the time of writing has yet to be described and named. According to DNA sequencing by Axel Meyer on specimens collected by Bleher, this new species is very close to the true Neon Tetra P. innesi, whereas the Cardinal Tetra P. axelrodi is genetically closer to the Green/False Neon Tetra P. simulans.
 
He definitely said Brazil - but that may not mean anything. If I have the chance I will try to go back to have a look at the weekend.

Based on your description the fish in my tank look like the Columbian form. These were sourced from the same shop several years ago.
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I would not jump to that conclusion, these may well be Brazilian. Here are some photos I collected, first two are the Brazilian form, then the Columbian which is quite different.
 

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Yes I see what you mean. In the absence of anything to compare them to I only looked at where the neon line ends. I guess there is a fine line between "at" and "below".
 
Byron posted a picture recently elsewhere on this forum that shows a Cardinal in the wild. Or maybe it was a link. Anyway, a thinking person could not possibly believe they could live, let alone thrive, in anything other than their own home waters that are very soft. I heard this myth myself and it sounded like baloney to me and I am glad to see it refuted.
 
Ahhh salesman.
Went back in at lunchtime today and spoke to another manager - they all seem to be managers in there. Only this one I have known for years and often go in for a chat with him if I am passing. Asked him to confirm that these were in fact from Brazil. He is going to check the paperwork but said he would be very surprised because (as far as he was aware) they only get Colombian stock of these.

They do look very similar to mine in appearance.

On a different note, but related by the subject of trustworthiness of the LFS, I managed to pick up a group of 7 Nannostomus marginatus to go with the 11 Nannostomus trifasciatus I previously bought from the same shop. On each occasion I wanted a large group and ended up buying everything they had! As I suspected from looking at them in the shop the fish in my main tank and QT are identical. So in a couple of weeks I'll have a decent sized group of pencil fish, but will continue to be in the dark about what they actually are.
 
Ahhh salesman.
Went back in at lunchtime today and spoke to another manager - they all seem to be managers in there. Only this one I have known for years and often go in for a chat with him if I am passing. Asked him to confirm that these were in fact from Brazil. He is going to check the paperwork but said he would be very surprised because (as far as he was aware) they only get Colombian stock of these.

They do look very similar to mine in appearance.

On a different note, but related by the subject of trustworthiness of the LFS, I managed to pick up a group of 7 Nannostomus marginatus to go with the 11 Nannostomus trifasciatus I previously bought from the same shop. On each occasion I wanted a large group and ended up buying everything they had! As I suspected from looking at them in the shop the fish in my main tank and QT are identical. So in a couple of weeks I'll have a decent sized group of pencil fish, but will continue to be in the dark about what they actually are.

It couldn't be easier to ID these two species apart from one another...look for the adipose fin. If they have it, they are N. trifasciatus; if not, they are not N. trifasciatus and more likely N. marginatus which does not possess an adipose fin. I'm sure I mentioned this somewhere recently, though looking back it was not this thread.

The Colombian cardinal can vary with respect to colouration, I have seen different-looking fish within the same batch. And they are more common. Exports from Brazil I've been told are not always easy.

Edited to correct. B.
 
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It couldn't be easier to ID these two species apart from one another...look for the adipose fin. If they have it, they are N. trifasciatus; if not, they are not N. trifasciatus and more likely N. marginatus which does possess an adipose fin. I'm sure I mentioned this somewhere recently, though looking back it was not this thread.
I did ask the question but we were digressing on someone else's thread. So assuming you meant "N. marginatus which does not possess an adipose fin" that settles it. Thank you.

It also confirms the ones I bought today were correctly labelled and the ones in my tank were not.

Edit: I just spotted the comment at the bottom of SF's description pointing out the error in the main text, which states it is missing the anal fin rather than adipose.

20190723_220853 (2).jpg
 
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I did ask the question but we were digressing on someone else's thread. So assuming you meant "N. marginatus which does not possess an adipose fin" that settles it. Thank you.

It also confirms the ones I bought today were correctly labelled and the ones in my tank were not.

Edit: I just spotted the comment at the bottom of SF's description pointing out the error in the main text, which states it is missing the anal fin rather than adipose.

View attachment 92736

Yes, that is N. marginatus. And I corrected my previous post...must read what I write more diligently. :thanks:
 

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