Bag Air

Q. I was going through the July 1997 issue of AFI when I read this department. Stephen Meyer, are you nuts? In response to a question about moving goldfish, you told the guy to put some water in a plastic bag, "blow into the bag" for air, and then tie it up for transport. You were kidding when writing this stuff right?

Remember back in physical science class: breathe in oxygen and exhale...carbon dioxide! I am sure that this guy's fish died in about 20 minutes after following your advice. I think you owe him a new fish for this false information.

I am writing this in detail so you can follow. When you bag a fish you can catch atmospheric air (which contains 20-percent oxygen) in the bag. Or better yet, shoot oxygen from an oxygen cylinder, or pump air from an air pump, or use a commercial oxygen supplement.

One more thing. I hope you don't maintain ponds, because your advice about dechlorinating was wrong. There is a simple solution for dechlorinating pond water when doing a water change (once again in detail so you can follow). Use a Python system hose fitted with a modular filter containing activated carbon. The carbon removes the chlorine and there is no need to worry about the fish.

A. Sorry you found my column so disagreeable. It is true the exhaled air contains a smaller percentage of oxygen and a higher percentage of carbon dioxide (CO₂) compared with atmospheric air. The difference, however, is negligible (unimportant) when you blow up a bag for fish for short hauls.

Really, think about it. The rapid breathing that takes place when you blow up a balloon (or give CPR) does not allow for much gas exchange in the lungs. If it was true that exhaled air had dangerous concentrations of CO₂, what do you think would happen when you gave CPR to someone? How many people have died from CO₂ asphyxiation after receiving CPR?

Yes, an air pump would be a good alternative, but not if you did not have an air pump. Yes, an oxygen cylinder would be a good alternative, but not if you did not have one — or were afraid of a fire hazard. I agree that an oxygen-rich air mixture would be a superior choice for long hauls. But, frankly, opening the bag and breathing fresh air into it a few times would do just as well.

Fortunately, you can tell when bagged fish need "fresh air" because the bag deflates as CO₂ replaces oxygen. It loses its tautness.

Fish are most likely to suffocate when the bag contains too much water. The volume ratio of air to water is more important under most conditions. Roughly, the bag should contain no more than 25 percent water. In fact, the great risk to transporting fish is not asphyxiation but 1) ammonia poisoning, 2) overheating or freezing, 3) leaks, 4) physical injury and 5) systemic stress from handling during the move.

Regarding the use of activated carbon for dechlorination, yes, it would work. But first, most pond water changes involve a hefty volume of water on a frequent basis, and therefore a hefty volume of activated carbon to do the job right.

Second, most pond water changes involve fairly rapid flows that would be significantly impeded passing through a carbon chamber. Water changes already take hours in my ponds using 1-inch hoses. Your approach would require a day or more. Third, it really is not necessary in most circumstances. On the other hand, for those who have small garden ponds (say, a few hundred gallons or less) your idea has lots of merit.

Thanks for writing. I think a smart reader should always have a healthy skepticism about the material found in magazines and books. I am glad to see you questioning the advice you read here.

About Winters
Q. I'm planning on building a pond this summer, but I need to keep the project costs down because we have a new baby and other more pressing expenses. I'm going to dig the hole myself. How deep does the pond have to be for the koi I plan on keeping to make it through the winter? I'm concerned with having to get rid of the dirt removed from the hole, and I know that the deeper the pond, the more dirt, and also the larger the liner I will have to buy.

A. Keeping koi outdoors all winter in the northern United States is problematic. The fish are sensitive to the cold temperatures, the decline in dissolved oxygen in the water, and the buildup of toxic gases (sulfur dioxide among other things) that occurs as winter progresses.

A few mild winters can produce a false sense of security, then the fish are wiped out by a more severe winter. Then, too, small koi seem to survive winters better than larger koi. This is due to the fact that the former can survive in lower oxygen concentrations. So, new pondkeepers (who tend to start with smaller fish) seem to have good overwintering success to start, only to end in disaster as their fish reach a larger size.

In New Hampshire I would recommend at least 6 feet of depth across most of the pond. A wide pond floor is a must so there is plenty of room down there. Water at that depth will stay a few degrees warmer than water a few feet up. And that difference in temperature can make all the difference in whether the fish survive the winter.

I also recommend several thermostatically controlled deicers to keep at least minimum gas exchange going at the surface. The previous writer's concern (see above letter) about fish suffocating is quite real in this context.

You can improve the gas exchange in the pond after the ice cover reaches its normal thickness (which might be 18 inches or more in your area). Once the ice thickness stabilizes, draw out about a half-inch of water from the pond. This creates an air boundary between the ice and the water, allowing the full water surface to exchange gas. The deicers will keep a wider area ice free for the rest of the winter.

Regarding the "extra" dirt, there are basically two choices. First, find a way to use it on site. Create some topography. Make hills. Use it to fill low spots in your garden. Build a waterfall. Or, second, have it trucked away. There are many construction sites looking for clean fill dirt.

Butterfly Koi
Q. I read the following in a water gardening magazine about butterfly koi: "Produced by crossing comet goldfish with koi carp, a butterfly koi proves to be hardier and smaller than its larger koi cousin." Do you agree? Everyone I have talked to about this claims that they grow just as large as other koi.

A. As a generalization it is probably correct. Comets, which are goldfish, are hardier than koi. They handle colder water temperatures better and they tend to handle lower dissolved oxygen levels better too. They are also definitely smaller than full-grown koi.

If you cross a comet and a koi, the offspring will tend to mix the genetic traits of both. On average, they should be larger than comets, but smaller than koi. They should have a hardiness somewhere between the two.

They should also have more coloration than comets. Many will have the flowing fins of fancy comets — but others will not.

Remember that breeders select for certain traits. They pair fish to maximize color, fin structure, or whatever they find interesting. (Others just let nature decide what happens and then they simply cull what will not sell. But this is still genetic mani<$>pulation.) Therefore, the characteristics of the butterfly koi available for purchase can vary widely from dealer to dealer. There are no standards.

There is also a down side to this genetic manipulation. A breeder pushing for a specific color pattern or finnage structure may also inadvertently introduce other genetic codes systematically into his or her fish. These animals may be less tolerant of cold than either comets or koi. They may be prone to physical deformities, tumors or be sterile.

I am not surprised by the observations of your friends. If butterfly koi seem to reach the same size as koi, it is probably because most hobbyists never get to see full-size koi. Too many pondkeepers think the natural life span of these animals is five years (because that is how long they last), and these tend to be 12 inches in length. By contrast, a nice 20-year-old koi, which is still a teenager in koi years, is big — more than 2 feet for just the body.