By Uncle Bill

One of the most important parts of the hobby is knowing how to cure disease. What I think is more important is preventing it. I'm sure that you've seen all the antibiotics, sulfa drugs, etc. on your dealer's shelves and read about which drugs are to be used (or recommended) for which diseases, many times by famous breeders. One of the first problems immediately becomes apparent: "What is the disease that my fish have?" Very few of us can tell and we certainly won't find out by reading the label. What I'd like to cover is probably the best way to prevent disease. In most cases, the best treatment is to allow the fish's natural defenses to cure itself.

The most exposed and important organs that a fish has are its gills. We all know that fish extract oxygen from and expel carbon dioxide into the water. The gills also perform another important function. They are the means by which fish excrete their nitrogenous waste in the form of ammonia. In mammals it is the kidneys that perform this function. They excrete these nitrogen compounds from the body in the urine. The gills also absorb ions of which sodium is the most important. In this way the gills actually help to maintain the balance of water and salt in the fish's body.

Because of their importance, when the gills become irritated the fish becomes stressed. This can be caused by the wrong temperature, pH, hardness, the level of dissolved carbon dioxide and of low levels of dissolved oxygen. Basically, stress is mostly caused by poor water quality or water that is of a different quality than what the fish requires. The major cause of poor water quality is not doing enough water changes. In most aquarium magazine articles a 10% water change is recommended. Why then do most breeders (whether of discus or guppies) change 25% and more (some change a lot more - up to 300% ) each day?

Stress not only affects the gills' ability to perform gas exchange and excretion, it affects the immune system as well. When a fish is stressed, the production of antibodies is reduced. This is when the fish needs them the most. When a fish appears stressed, the usual thing that is done is to treat the fish (most times the entire tank) with antibiotics. In most cases, the actual amount of antibiotics present in the medication is not labeled so one has no way of knowing the dosage being administered. Much of the time the dosage is too low and the hobbyist is actually helping to develop a strain of resistant bacteria. Another popular method of treatment is "dipping". A fish is dipped in a solution of, for example, malachite green, potassium permanganate or other poisons. That's right, poisons! This procedure further irritates the gill tissue thereby causing more stress. Even if the parasites are killed, unnecessary damage to the gills may be caused with this method.

The most effective treatment for an unknown disease (and, let's face it, most of the time we haven't the slightest idea of what the problem is) is making a 50% water change and raising the temperature by 10 degrees Fahrenheit (3C degrees). Depending on the fish, one can increase the salinity by adding non-iodized table salt over a period of three days until a level of 2.4 tsp./gal. has been reached. Be sure that the fish to be treated can tolerate the salt. Many scale less fish and others such as cardinal tetras can not. By adding salt, you are temporarily reducing the amount of energy being spent by the fish to maintain the salt to water balance. Saltwater fish "drink" water and freshwater fish expel it. This is because a freshwater fish's body has a higher concentration of salt than the surrounding water. Freshwater is absorbed into the body by a process known as osmosis. The opposite is true of saltwater fish. So, by increasing the salinity, we have reduced the amount of energy being spent to expel water (less water in, less water out). The fish now can better direct that energy into fighting a disease. Raising the temperature serves to increase the body's metabolism and stimulate the appetite. Raising the temperature is also the best way to treat "ich". Keep the temperature 10F (3C) degrees higher than normal for 10 days and the "ich" (the disease is sometimes called "white spot" because it looks like someone sprinkled salt all over your little fish) should be gone. Increase the amount (double) and frequency of water changes at this time.

By using the above techniques, you will both stimulate the fish's immune system and help the gills in performing their all-important tasks. Reduce the stress and you have gone a long way towards reducing disease.


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