Method of preparing the treatment solution.
Antibiotics should be used only in extreme cases, in obvious forms of disease. They should be used when there are no alternative remedies, or when other remedies have proven ineffective. Do not use antibiotics without making an accurate diagnosis. They are often ineffective because bacteria have already developed resistance due to years of misuse. A course of antibiotics must be completed even if symptoms of the disease have disappeared. You do not want to cultivate a strain of microorganisms immune to the given drug. For the same reason, do not treat “just in case” with a half-dose.
Medicines, especially antibiotics, have an expiration date. This is obvious, but nevertheless, check the expiration date on the package. Before applying medication in a general aquarium, perform a large water change, up to 50%. This refreshes the water and removes organics, a high concentration of which neutralizes many drugs. To remove organics before medication application, activated carbon can be added to the filter. Do not forget to remove it afterwards, as it absorbs many medications. Turn off the UV sterilizer and ozonizer.
Some preparations have a negative effect on the nitrogen cycle bacteria in the aquarium. Therefore, treatment with such preparations is best carried out in a quarantine aquarium or by removing the biofilter media and keeping it separately in a container with intensive aeration. After treatment is completed, it is necessary to monitor ammonia levels and change water more frequently.
The dosage is set 100 times less than for humans. If a dose of 15–30 mg per kg of body weight is established for humans, this dosage can be adopted for 1 liter of water. In a 100-liter aquarium, 1.5–3.0 g of these substances are added. Treatment is carried out for 7 days or more.
Different medications must not be used simultaneously, as their combined effect can cause poisoning. Manufacturers usually indicate compatible drug combinations. If you use medications sequentially, make sure there are no traces of the previous medication left in the water before applying the next one. Be sure to complete the recommended course of treatment. If you fail to do so, the disease will remain uncured. The fish will be weakened by the chemicals, making it harder for them to withstand the illness. In other words, incomplete treatment can cause the disease to flare up even more.
Stock and working solutions.
Aquarium medicines are most often sold in the form of a stock solution with specific dosage instructions, which must be strictly followed. There is no need to change the concentration of these drug solutions. The dosage for many drugs is related to a stock solution (e.g., 3% hydrogen peroxide solution). In such cases, the chemical is purchased in dry form, and a stock solution is prepared from it. It is easier to accomplish this task using metric units, where the percentage figure expresses the number of grams of the chemical to be dissolved in one liter of water (e.g., a 1% solution is 10 grams of the chemical per one liter of water, or 1 g per 100 ml of water).
The treatment solution obtained by adding the required dose of the stock solution or dry chemical to the water where fish are to be treated is called the “working solution.” For example, a 20% stock drug solution needs to be introduced at a dosage of 3 ml per liter of water. Then the working concentration is calculated as follows: 20% × 3/1000 = 0.06%, i.e., we get a 0.06% solution. Sometimes (but not always) the stock and working solutions have the same concentration, meaning the stock solution is used “neat.” This happens, for example, when it is applied topically or introduced into food. It is extremely important to treat fish using a properly matched working solution and never expose them to a higher concentration of the drug, otherwise, serious harm or even death may be caused.
However, during the preparation of the stock solution, the aquarist may face many problems. They may lack the equipment (laboratory scales) needed to weigh chemicals in very small quantities required to prepare a convenient volume of the stock solution. The aquarist has an alternative — they can take a larger amount of dry substance and water. But in this case, they will face the problem of getting rid of excess solution or storing it. Therefore, it is preferable to purchase a ready-made stock solution if possible.
Sometimes the stock solution available to the aquarist differs in concentration from the one needed for treatment. Do not allow medication overdoses — this is unlikely to speed up treatment and may kill the fish. For example, an aquarist found a stock solution of drug “X” with a concentration of 30%, but the recommended dosage is given for a 6% stock solution. In such cases, there are two options.
1) The stock solution can be diluted to the recommended proportion (in cases where a weaker solution is required). Thus, using the example of drug “X” above, one part of the 30% solution is combined with 4 parts of a diluent (e.g., distilled water) to obtain the required 6% solution. After that, the recommended dosage can be used.
2) The dosage can be recalculated to compensate for the difference in stock solution concentration. For example: the recommended dosage is based on a 40% stock solution of drug “Y”, which needs to be dissolved in aquarium water at a ratio of 2 ml per liter of water. However, the aquarist has a bottle with a much weaker, 5% stock solution of drug “Y”. To compensate for the difference in strength, divide 40 by 5 and multiply by the dosage. Thus, 40 : 5 = 8, multiplied by 2 ml/liter = 16 ml/liter. Therefore, the aquarist must introduce the stock solution at a ratio of 16 ml of solution per liter of water.
Dissolve the amount of preparation for the entire aquarium volume thoroughly in a 200 ml glass. Then pour this solution into the water in equal portions in 3 steps, every 30 minutes, and turn on the aerator for quick mixing. Do not pour the entire solution at once. A fresh solution must be prepared for each application. For treating juveniles and weakened fish, a less concentrated solution is used.
Acriflavine, Collargol, Masoten, Neguvon, Niclosamide, Nitrofuran, Copper sulfate, Trypaflavine, Trichlorfon, Formalin, Chloromycetin are toxic and poisonous, so their application and especially dosage must be very careful. Care must be taken with Bicillin-5, Malachite green, Potassium permanganate, Sodium chloride, Trypaflavine — they have a negative impact on fish and plants.
Internal administration of medications via food.
This method is used to treat systemic infections or combat intestinal parasites. Prescription medications, including antibiotics, are used for this purpose. The main benefit of internal administration is that the drugs go directly into the gut, making them extremely effective for eliminating intestinal parasites and pathogens. Furthermore, many medications penetrate the internal tissues of the body better through the gut than through the skin.
For this reason, internal administration for treating systemic infections is generally much more effective than bath treatments. Another advantage of this method is that only affected fish can be treated. True, this requires moving them to a separate aquarium, at which point all the advantages of separate treatment become apparent.
However, this method has serious drawbacks. Sick fish usually refuse to eat, especially when moved to an unfamiliar environment. If several fish must be treated together, there is no guarantee that each will eat the necessary amount of medicated food. Fortunately for aquarists, drug doses are often expressed in units of drug weight relative to food weight rather than fish weight. It is specified how often fish should be fed medicated food over a certain period. Medicated food must be prepared specially. Ready-made flake or pellet fish food infused with medications is available for purchase in pet stores.
Medication can be incorporated into food as follows: first, dissolve the drug in a small amount of water, and then soak the food in this water. Food particles must be of a suitable size for the fish being treated. When preparing food for systemic infections and intestinal parasites, dry flake or pellet food is moistened (or soaked) with the drug or its solution. Mix thoroughly, dry, and store in a small, tightly closed jar in the refrigerator.
A gelatin solution can be used to bind the medication more securely to the food and minimize leaching into the aquarium water. Mix the medicine with bloodworms, which are a tasty food for fish. In addition, dissolved medication can be injected into earthworms to stimulate the appetite of large fish.
Due to the high moisture content in such homemade medicated foods, they are particularly prone to rapid mold growth. Therefore, they should be stored at low temperatures. Leftover medicated food should not be fed to healthy or recovered fish (as this risks developing pathogen resistance to the drug). If the food cannot be stored for future use, it should be discarded.
Effect of medications on biofilter functioning.
So, you have a well-established aquarium, running long enough for the biological balance to be fully established, ammonia and nitrite levels close to zero, and nitrate levels also low. And in this aquarium, an outbreak of disease occurs, introduced by a new fish. We begin administering medications, but how do they affect other microscopic inhabitants of the aquarium, such as nitrifying bacteria?
When various medications are used in an aquarium, partial or complete suppression of biofiltration processes occurs in most cases. This is because most diseases of aquarium fish and other inhabitants share the same biological nature as the biofiltration processes themselves. Thus, aquarium medications, while suppressing pathogens, simultaneously have a similar effect on the bacterial colonies participating in biofiltration processes in the aquarium. Be sure to check the instructions to see if the intended medication will adversely affect biological filtration.
When biofiltration is disrupted, various harmful elements begin to accumulate in the aquarium that previously converted into less toxic forms through biofiltration. As a result, water quality deteriorates, affecting fish health. A sudden spike in ammonia or nitrite concentrations can be more harmful to fish than the disease itself or act as the “final straw.” This very factor may cause fish health to decline after the treatment course is finished, when the danger seemingly has passed. Practically all preparations suppress the nitrification process to some extent; those with minor suppression are less dangerous, but some affect it severely, up to a complete halt of nitrification.
What steps should be taken to prevent aquarium water quality from deteriorating despite treatment? It is primarily about water changes. Under conditions of impaired or completely destroyed biofiltration, fish metabolic waste products cannot undergo normal transformation and accumulate in either primary or intermediate forms. In other words, the concentration of ammonia and/or nitrite begins to increase in the aquarium water — substances much more harmful to fish than nitrates, which waste normally converts into.
Thus, water changes that were previously sufficient in a normally functioning biofilter aquarium, removing mostly less toxic nitrates, cease to be adequate because other, more toxic substances must now be removed instead of nitrates. And since these substances are far more toxic to fish and other aquarium inhabitants, even their minor concentration — perfectly acceptable for nitrates — becomes lethal and incompatible with the life of aquatic organisms.
Water changes must be increased not only during the treatment period itself but also during the recovery period of normal biofiltration in the aquarium (at least two weeks). It is necessary to increase the frequency of substrate vacuuming to quickly remove fish waste from the aquarium. With a normal fish stocking density, this means 20–30% water changes of the total aquarium volume every 1–2 days, simultaneously cleaning debris from the substrate while changing water.
In addition, the aquarium filter and its media should be thoroughly rinsed, preferably with tap water rather than aquarium water in this case. After applying medications, bacterial cultures should be used to support the normal functioning of the biofiltration process. All these actions will help get rid of drug residues dissolved in the water, as well as those remaining in the substrate and filter media.
How to remove medications and chemicals.
If the medication does not dissipate naturally, at the end of the treatment period it must be removed from the aquarium either through multiple partial water changes or via chemical filtration — depending on which method is best suited for the specific drug.
