Believe me, you don't want to eat those fish anyway. They taste like metal.
Another way to get CO2 is by mixing some yeast and sugar water. That will make almost pure CO2
(and alcohol). It's probably a good idea to boil the water first to remove most of the dissolved air. Let it
cool below 70° before adding the yeast or else it will die. Also try and keep the air out of the system or
else the yeast will begin to do other things you don't want and won't make alcohol. The "reaction"
doesn't happen right away, either. The yeast cells need time to grow and divide. A lot of the
commercial CO2 comes from breweries. I wouldn't advise drinking it either because if it's not done right
it can make you sick. You might be able to do other things with the alcohol, though.
To dry it out, sillica gel will work, but it has to be dry. The kind with the indicator is the best. It will
change colors to let you know when it needs to be "recharged". It works best if the gas has a little time
to "soak" in the gel. You can also use crushed calcium chloride, in fact that will work a little better.
You can find it in some types of ice melter (peladow). It has be be heated to a fairly high temperature
first to drive off most of the moisture. Just throw it in a stainless steel or pyrex lined pan that you don't
care much about.