četvrtak, 16. rujna 2010.

SALT IN THE FRESHWATER AQUARIUM

Much has been written about the pro's and con's of adding salt to an aquarium. Some support its use unequivocally, while others condemn it outright. As usual, the truth lies somewhere in the middle.

Why would we want to add salt in the first place? After al, there are a few fish that do not do well with any salt at all in the water. Some fish that do not do well with added salt would include smooth skinned catfish, Corydoras, Tetras, Angelfish, Discus, Loaches and Bettas. There are others as well. High concentrations of salt also are detrimental to planted aquariums.

Some fish that do much better with added salt would include Goldfish, Koi, African Cichlids, and livebearers. Indeed, the secret to keeping healthy, robust Mollys, Platys, Swordtails, and Guppys is to add salt. Many Ichthyologists consider Mollys and Platys to be saltwater fish that have been adapted to freshwater, and not the other way around. Almost all health problems with Mollys disappear when salt is added. Mollys can actually thrive and reproduce readily in straight seawater. Some saltwater aquarists use Mollys as "cycle" fish in their saltwater aquariums. The usual recommended dose is 1 tablespoon of aquarium salt per 5 gallons of water. This does does not seem to harm most plants, but higher doses may.

Some people keep mixed community aquariums to include both Mollys and Tetras, Platys and Corys. I have kept these fish in water with added salt for years, and have never noticed any particular problems to the Corys or Tetras, although they will not readily breed in water with any salt added. Corys and Tetras can best be bred in soft, slightly acid salt-free water, so that may be a factor for you if you wish to keep these particular species for breeding purposes. You may not want to keep Corys and Tetras intended to be bred in community tanks with added salt.

Advantages of added salt include better osmosis balance for the fish (who must maintain a proper internal/external balance of water). Salt also reduces or eliminates nitrite toxicity. In a cycling tank, nitrites can be quite toxic, but not with added salt. Indeed, marine fish are completely free of worries from nitrite toxicity due to the high salt content of seawater. Experiments with nitrite levels as high as 25 ppm cause no problems for saltwater fish. A similar effect can be expected with freshwater fish, although of course we will not be adding salt at the same rate as for saltwater fish. Salt also reduces parasite infestations, since salt interferes with the life cycle of many (or most) external parasites.
Salt can be used with almost any fish on a temporary basis as a therapeutic medication for most parasites, particularly Ich. Many fish cannot be treated with the usual Ich medications such as those containing Malachite Green. Tetras and Corys in particular can be seriously harmed with ordinary Ich medications. However, all fish can tolerate 1 tablespoon of salt per 5 gallons of water for the 21 days it takes to eradicate Ich. Raising the water temperature to 86-88*F is recommended to treat Ich because it speeds up the life cycle of the parasite, and also seems to create a hostile environment for the parasite, while not harming the fish. After 21 days, the temperature may be lowered by returning the heater to its previous setting and allowing the water to cool naturally. Salt may be removed by routine water changes, which will slowly dilute out all the salt, if that is your desire. Or, if you are maintaining fish that prefer salt, you can replace lost salt at the rate of 1 tablespoon of salt per 5 gallons of water changed.

Which salt to use? Well, aquarium salt (such as Aquarium Pharmaceutical's Doc Wellfish brand) is readily available in any fish store, and a box goes a long way. Table salt contains additives which you may not want in your tank. Most opponents to table salt cite the addition of Potassium Iodide to the salt, but I do not believe this is a concern. However, many brands of salt contain anti-caking agents such as Yellow Prussiate of Soda, which contains Cyanide. Yes, the dosage is quite small, but why would you WANT to add something potentially harmful to fish when there are readily available alternatives. If you should happen to live, say, 30,000 miles from the nearest aquarium store and you have no telephone with which to order salt from one of the mail order companies, then you can use Morton's Rock Salt, or Hain's Sea Salt, readily available from your supermarket. Kosher salt is frequently recommended. Unfortunately, Morton's Kosher Salt contains Yellow Prussiate of Soda, so I do not recommend its use. If you can find it, canning salt also makes a good alternative; it's usually additive free.
If you are a planted aquarium aficionado, you would probably be best advised to avoid adding salt to your aquarium. If you have fish that prefer salt, perhaps it would be better for you to keep your fish and plants in separate aquariums. If your primary goal is to grow beautiful plants, and if your fish require much salt, then you have a decision to make. You can favor the plants, or you can favor the fish, but where salt is concerned, it's rarely possible to do both.

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