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Re: "breathable" bags

David Robinson writes:

> While breathable bags are certainly available now, many fish stores do not
>  go through the added expense of using the bags that are sufficiently
>  permeable
>  to support fish life for extended periods of time.  I submit this response
>  not
>  to be argumentative, but to prevent an unknowing user from taking this
>  advice
>  and believing fish can be easily maintained for long durations without
>  either
>  using high oxygen content in the bag or changing the air every twentyfour
>  hours.
>  If you know that your store truely uses breathable bags, then the fish can
>  safely
>  be kept for extended periods without the use of supplemental O2.
The "non-breatheable" bags which have been in the trade for decades also 
breathe.  The difference between the two is that the new breatheable bags 
breathe where they are wet on the inside, and the older standard bags are 
breatheable where they are dry.  That is why the standard bags are usually 
only filled about a third of the way but bretheable bags are filled 
completely.  The breatheable bags allow one to get more bags of fish in the 
same size container, or to use smaller shipping containers.  As I see it, 
this only means less available O2 in the container for the fish.  I continue 
to use the older bags and larger containers, so my fish have more air 

To demonstrate this concept, pick a couple of fish you don't particularly 
value, of the same species.  Put the smaller one in a jelly jar  with one 
third water, and seal the lid.  Put the larger one in a bag about the wame 
size as the jar with about the same amounts of air and water.  The large one 
will use more air, but still survive the smaller one, which will be dead 
within 12-18 hours, depending on the size of the fish and the size of the 
jar.  The bag is selectively permeable to O2 and CO2, and the larger fish 
will be just fine, assuming the bag and jelly jar are of appropriate size, 
proportionate to the fish.

Bob Dixon