Theory on Impaction

[blueberlin]

Those of you who know me, know that I like to think up unfounded theories. I have a new one now and thought I'd toss it up for debate. :happy:

Fact 1: Common instructions on axolotl care stipulate that substrate of gravel/pebbles larger than 3 mm and smaller than an axolotl's head can be swallowed and "lead to impaction".

Fact 2: Several people have asserted, contrary to Fact 1, that they have kept their axolotls on a gravel substrate for years with no problem.

Fact 3: Some people have bought axolotls from a pet store that kept the animals on coarse gravel and kept the axolotls on a sand substrate, but still had problems with impaction, although the problems did not arise for months or even years later.

Fact 4: A mixed substrate of sand and gravel is dangerous because the sand fills in the gaps between the gravel, creating an airlock. (etc.)

Theory: Gravel can churn around in an axolotl's system without necessarily causing a blockage, but when sand is later ingested, it can "fill in the gaps" with the gravel and cause impaction.

Thoughts?

-Eva

 

[Andrew51]

With all your above stated facts, couldn't it then be possible that if the axolotl were to eat enough sand alone, impaction may occour?

If this is tha case then a bare tank floor is the safeest option (as always)

In regards to having an axolotl live on gravel or pebbles for many years and not have any problems, then all i can assume was that the owners got lucky the axolotl did not swallow any stones large enough to create a blockage. Like I read in another thread, someone had one axolotl on gravel, then placed him in a bare bottomed tabnk only to find pieces of gravel on the floor days later....

 

[blueberlin]

With all your above stated facts, couldn't it then be possible that if the axolotl were to eat enough sand alone, impaction may occour?

Ah, but sand will shift and churn - unless, so goes my newest unfounded theory, it runs up against a pocket of gravel. Now we have the makings of cement!

-Eva

 

[Andrew51]

And from all my childhood saturday morning cartoons, this could only lead to eventual hilarity!!

In all seriousness you are definately on to something, now you have established that this sand/gravel mixture would/may result in impaction, but is there a possibility it could also occur with sand alone?

 

[blueberlin]

There is a rumor that keeps surfacing that sand can cause impaction but it is, to the best of my knowledge, unfounded. (Which doesn't mean it can compare to my theory... um... )

Sand can even pass out from the mouth through the gill slits during feeding.

-Eva

 

[Andrew51]

There is a rumor that keeps surfacing that sand can cause impaction but it is, to the best of my knowledge, unfounded.

Ok good becuase my tank is sand

Now in regards to your theory, I completely agree that there is the possibility that the gravel and sand would cause an impaction, but it will remain unfounded becuase I'm not really willing to test the theory

But one would also ask, wouldn't the sand just pass through the system as if the gravel were not present? The gravel stone may not actually act as a complete blockage as one might assume...

 

[blueberlin]

I have sand in all of my aquaria, too.

-Eva

 

[optimist]

I wonder how they cope in the wild -- what is the substrate in their indigenous Mexican lakes comprised of? Seems to be a bit of a design fault in axies -- this gulping down of anything they can get their mouths around

 

[Darkmaverick]

Eva,

Thats such an interesting thread.

According to Axolotls by Scott., P.W., the Lakes Xochimilco and Chalco are fed by clear springs and taken up by floating islands of peat tangled with rushes, moss and grass while the bottom of the lake are fertile mud and sand which the locals used as fertiliser. There might be an odd pebble or two but generally in the wild, mud and sand would probably feature greatly.

Therefore i think in general sand would still be a safe option but i think it also depends on the axolotl. Perhaps some axolotls have poorer constituition or have a concurrent gastrointestinal problem that predisposes them to impaction.

I would not want to risk it with gravel though. Its just not logical to increase the risk.

 

[bethd217]

Sorry if I'm just being dense, but could someone explain again why a mixture of sand and rock is bad? I know that just sand is OK, and I would imagine that a sand tank with a few rocks scattered on top of the sand would also be fine. But somehow as more and more rocks get added, suddenly there's a problem? I saw the reference to an "airlock" effect, but I don't quite understand what that means and how it would be different from a pure sand tank, which nobody complains about.

 

[ferret_corner]

Ok Beth,

Have you ever siphoned a tank and had a piece of gravel get sucked up and into the opening that leads to the flexible tube?

I have. Water is still going around the gravel bit, although slower. Now imgaine that piece of gravel is stuck there and small amount of sand comes along with some detritus, the sand/detritus (or sand/food) combo fills the tiny gaps around the pebble and causes a complete impaction. Water can no longer get through at all.

Does that help?

 

[blueberlin]

Ok Beth,

Have you ever siphoned a tank and had a piece of gravel get sucked up and into the opening that leads to the flexible tube?

I have. Water is still going around the gravel bit, although slower. Now imgaine that piece of gravel is stuck there and small amount of sand comes along with some detritus, the sand/detritus (or sand/food) combo fills the tiny gaps around the pebble and causes a complete impaction. Water can no longer get through at all.

Hey, Sharon understands my theory! And describes it really well. C'mon lady, let's set the scientific world on its ear!

Sorry if I'm just being dense, but could someone explain again why a mixture of sand and rock is bad? I know that just sand is OK, and I would imagine that a sand tank with a few rocks scattered on top of the sand would also be fine. But somehow as more and more rocks get added, suddenly there's a problem? I saw the reference to an "airlock" effect, but I don't quite understand what that means and how it would be different from a pure sand tank, which nobody complains about.

Beth, sometimes people have gravel in their tank and then instead of chaning it out, they put sand on top. In time, the sand will settle in between the gravel. This creates a sort of cement which can turn foul and negatively influence water quality.

Sand can do something similar, indeed, if it is too thick - in this case, though, it forms air pockets which then foul. The way to prevent this is mainly just to keep your substrate thin - an inch (two, three cm) or less. If the sand is deeper, you need to stir it up when you do water changes - I run my feeding tweezers through it and watch the pretty little bubbles float up, but you can use your fingers, too.

-Eva

 

[Darkmaverick]

Hi beth,

A mixture of rocks and sand will create all these nooks and crannies that can trap accumulated wastes and uneaten food which can foul your water quickly. They are also harder to clean out.

Eva/Sharon - I agree with your gravel and sand hypothesis. Logical.

Cheers

 

[blueberlin]

Hi beth,
Eva/Sharon - I agree with your gravel and sand hypothesis. Logical.

Indeed, dear, that is the point of an unfounded theory. It is supposed to sound logical, but is not based on any real evidence. Tee hee.

The flaw becomes more obvious if one begins to base advice on such a theory. For example, based on my theory, I would advice keepers with pets from a pet shop where the axolotls were kept on gravel to have no substrate in their aquarium for at least three years. Otherwise, the axolotl may become impacted and die.* See what I mean?

*Disclaimer: Just to be really, really safe, I wish explicitly to note that this statement is merely to illustrate a point and should not be taken as real advice.

-Eva

 

[kira]

You know what? I think your on to something there!

 

[bethd217]

Hmm...

Honestly, not all of the explanations given make sense to me. I think I understand what is meant by the "airlock" effect now (yes, I have siphoned a rock substrate), but I'm still not sure how that would be "dangerous" to an axolotl, since presumably the rocks would be too large for the axolotl to swallow anyway. And it will definitely take a more developed argument to convince me that rock plus sand has more nooks and crannies than just rock -- shouldn't it have less, since the sand fills in some of them? (I currently have a tank with a rock substrate that I'm probably going to switch to sand soon because I'm tired of dealing with all the nooks and crannies.)

However, learning that pure sand can cause these problems by itself, I guess I can see how having big heavy rocks embedded in the sand might make it harder to get the sand sufficiently stirred up to stay clean. So that explanation does make sense to me, and I will make sure to swap out my rocks before putting in the new sand. Thanks, everyone!

--Beth

 

[Abrahm]

And it will definitely take a more developed argument to convince me that rock plus sand has more nooks and crannies than just rock -- shouldn't it have less, since the sand fills in some of them?

Hi Beth, the problem isn't that there is more nooks and crannies. The real problem is that a thick sand layer or a thick sand and gravel layer can pack really tightly. Sand and gravel or just sand will settle over time causing the part farthest from the water column to eventually lose all of its oxygen as creatures that live there use it and it can't be replaced by the water above. This environment without oxygen is called anaerobic and certain types of bacteria, also called anaerobic, will start living there. That's where the real problem starts as these bacteria produce a poisonous gas as a metabolic byproduct (just like humans produce carbon dioxide as part of respiration.) If the substrate is disturbed than it will release the gas in the water column where it can poison the animals.

As for Eva's hypothesis I am inclined to disagree. I don't think the gravel and sand is the problem I think it is just an issue of the speed at which the gravel is moving through the animal's GI tract. That's my 2 cents.

 

[ferret_corner]

so um what is a safe creature to put in our tanks that will crawl through sand but isn't harmful to the newts or axolotls? Aren't there underwater worms that do this?

Sharon

 

[IanF]

It makes sense Eva. However in my case my Axolotls were never kept on sand and 6 months after being removed from gravel they died of impaction. Mabey it just varies like you have said.

 

[Jennewt]

Your theories are always fun, Eva, but I remain skeptical. Where did Fact #4 come from?