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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
available.
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