Prevention of aquarium environmental problems.
Many environmental problems can be avoided with good aquarium care. You need to provide the aquarium inhabitants with a suitable environment, maintain good water quality, and ensure general aquarium hygiene. If a future aquarist is not ready to take on all the associated hassle, they should simply abandon the idea of keeping fish.
However, if the aquarium was properly planned and set up from the beginning, then maintaining optimal conditions generally depends on daily care and common sense – for example, not overfeeding fish or allowing overpopulation. In addition, it is extremely, crucial to avoid sudden changes in environmental parameters. Such changes can be extremely dangerous and often fatal. Not only regular equipment checks are necessary, but also close observation of the fish, which themselves serve as an excellent early warning system for emerging problems.
Clamped fins, rapid breathing, trembling, and scratching are all actions that can be transient reactions to temporary irritation or stress. But the same actions can be the first sign of something more serious. Therefore, it is worth conducting an additional check to ensure that the fish’s behavior has returned to normal. If several fish behave abnormally, this is a clear alarm signal. Therefore, water parameters must be checked immediately.
Most aquarists assume that any health-related problems in fish are caused exclusively by pathogens or parasites. In reality, most diseases arise from a poor living environment. Therefore, living conditions should be improved without resorting to medications. If it is established that fish are affected by some infectious disease, unfavorable environmental conditions still lead to its outbreak. If the signs of the disease are ambiguous, pay attention to the details of your aquarium maintenance and other particulars of the situation; this often helps eliminate a fairly large number of items from the list of diseases.
What steps need to be taken to ensure that water quality in the aquarium does not deteriorate? It’s simple. It’s primarily about water changes. By not changing water, but only topping it up, you risk turning your freshwater aquarium into a swamp. Under normal conditions, during biofiltration, fish waste products are converted into forms less toxic to fish. Under degraded or completely destroyed biofiltration conditions, fish waste cannot undergo such a transition and accumulates in either primary or intermediate forms. When biofiltration is disrupted, various harmful elements begin to accumulate in the aquarium, which previously were converted into a less toxic form during this very biofiltration.
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, into which fish waste converts under normal biofiltration. Thus, previously sufficient water changes (20-30%) in an aquarium with normal biofiltration, which mainly remove less toxic nitrates, cease to be such, because instead of nitrates, other, more toxic substances must now be removed with water changes. And since these substances are more toxic to fish and other aquarium inhabitants, even their insignificant concentration in the aquarium, which is quite acceptable for nitrates, is already deadly and incompatible with the life of aquarium hydrobionts. As a result, water quality deteriorates, and consequently, the health of the fish.
To reduce the load on the aquarium’s biological system, the amount of waste produced by aquarium inhabitants should also be reduced. The recommendation to reduce the amount of food for sick fish would in some cases be wrong, although effective, which leaves only one option – to limit the duration of these waste products staying in the aquarium to minimize their harm. This leads us to the necessity of frequent vacuuming of the bottom and substrate to quickly remove fish waste from the aquarium.
For more precise control of biofiltration status and determining the required level of water changes in the aquarium, it is recommended to use aquarium liquid drop test kits from various manufacturers of medications and aquarium equipment. You will need tests to determine the concentration of ammonia/ammonium, nitrite, nitrate, and preferably tests to determine water acidity/alkalinity in the aquarium. The latter test should be used together with the ammonia/ammonium test to determine the ratio of toxic ammonia to relatively harmless ammonium. The general rule is: the higher the alkalinity level (pH) in the aquarium, the more toxic ammonia will be in the ammonia/ammonium ratio, and the lower its concentrations permissible for aquarium water.
What to do with an overgrown, dirty aquarium? Try to break the treatment down into several stages and provide additional water aeration. Collect detritus from the substrate, perform a partial water change, and rinse the filter. The next day, remove old leaves and excess plants, change some water, and rinse the filter again. The next day, wipe the glass, change some water, and rinse the filter.
What should be done after finishing treatment in the aquarium? After completing the course of treatment, thoroughly vacuum the bottom and substrate in the aquarium. In addition, thoroughly wash the aquarium filter and its filter media; in this case, it is better to use running water rather than aquarium water. Next, continue performing forced water changes for some time. All these actions will help get rid of medicine residues dissolved in the aquarium water, as well as those remaining in the substrate and filter media. In addition, larger-than-normal water changes are required to remove toxic substances from the aquarium until biofiltration recovers.
Prevention of diseases caused by ammonia, nitrates, and nitrites.
As a result of organic matter decomposition in water, ammonia and nitrates appear. They are toxic and can cause fish poisoning even in relatively clean aquariums with old water. Dirty filters pose a special danger.
Ammonia is a product of protein metabolism. In fish, it is excreted mainly through the gills. It is also produced during the nitrogen cycle. In a closed system like an aquarium, ammonia can reach toxic levels unless removed through effective chemical or biological filtration and regular water changes. High levels of free ammonia in the water are caused by overpopulation, overfeeding, other sources of organic waste (dead plants, fish, snails, etc.), lack or absence of biological filtration, or a combination of these factors. Fish packed in transport bags face particularly high danger if there are too many of them or if they were heavily fed beforehand.
Ammonia is a potent poison even in low concentrations. As dissolved ammonia, it can be present in dangerous amounts in aquarium water when its pH is above 7.5. If the pH is lower, it will not be free ammonia, but ammonium, which is less toxic, but according to recent studies, not much better. Fish simply die from ammonia immediately, and from ammonium a bit later. Sometimes this “bit” can stretch to a month or more. Test kits detect both ammonia and ammonium indiscriminately, which is good since both must be fought.
Symptoms: Hyperactivity, loss of coordination, fish lingering near the water surface and gasping for air, attempts by fish to jump out of the aquarium. Gills are particularly damaged, with excessive mucus production and capillary hemorrhages. Signs of ammonia excess, protein overload, and decay products can be identified by persistent foam from a working air diffuser. Air bubbles that rise to the surface should pop within 1-3 seconds. If this does not happen, it means they are in excess in the aquarium. You should know that bringing nitrogen toxin concentrations to a critical point can happen very quickly, within 1-3 days. Poisoning can be avoided by weekly water changes and reducing aquarium stocking density.
Nitrates are the end product of the nitrogen cycle. Nitrates are less toxic to fish than other nitrogen cycle products. Although aquarists measure nitrate levels and consider them the cause of all troubles arising at high concentrations, other toxic byproducts accumulate in parallel with nitrates, even though their concentration is not measured. These very byproducts may be the real cause of diseases affecting fish. Nevertheless, high nitrate concentrations can be considered an indicator of poor water quality and point to the need for corrective action.
We speak about nitrate concentration and toxicity in accordance with standard aquarium practice. However, it should be remembered that some nitrate reduction methods (water changes, reverse osmosis) simultaneously reduce the concentration of other chemicals. There are other ways to remove nitrates – for example, using ion-exchange resins, but there is too little data regarding their impact on other chemical substances. Nitrates have a chronic rather than acute effect. Prolonged exposure to excessive nitrate concentrations (for a given fish species) can lead to stunted growth, chronic stress, general poor health, and reluctance to breed. It can make fish more vulnerable to other diseases.
Nitrate concentrations in the aquarium should be measured constantly to ensure they remain within safe limits. Good aquarium care, avoiding overpopulation, sensible feeding, and regular partial water changes will help prevent problems associated with high nitrate concentrations. Nitrate test kits sometimes have a limited shelf life, lose sensitivity over time, and constantly read zero. Tablet test kits have a distinct advantage over liquid ones in this regard: they remain functional longer.
Nitrites are formed during the nitrogen cycle as a breakdown product of ammonia. Nitrites are toxic to fish, though less so than ammonia. Nitrites harm fish by damaging their respiratory system. Through the gills, they enter the bloodstream and cause the oxidation of hemoglobin (the oxygen-carrying pigment in red blood cells) into methemoglobin, which is incapable of effectively transporting oxygen. High nitrite concentrations can cause symptoms characteristic of acute poisoning, as well as death from hypoxia. Prolonged exposure to slightly elevated nitrite levels, although relatively rare, causes general health deterioration and immune system suppression, similar to other forms of chronic poisoning.
Prevention of diseases caused by changes in water hardness and acidity.
Osmotic regulation is the process by which fish maintain a proper water-salt balance in their bodies to ensure optimal internal conditions for various physiological and biochemical processes. In all fish species, the osmotic regulation system has evolved to maintain water-salt balance at the chemical composition characteristic of their natural habitat. If the osmotic regulation system is overloaded due to prolonged exposure to unsuitable conditions (osmotic stress) or a sudden sharp change in water chemistry (osmotic shock), the fish may be physiologically unable to cope.
If fish accustomed to very soft water are kept in very hard water, calcium ions absorbed through food and gills begin to form calcium phosphate crystals that clog kidney tubules. Body poisoning occurs. Chronic osmotic stress can eventually lead to death, and osmotic shock can result in death very quickly.
If the natural impermeability of the skin is compromised due to injury or disease, water will enter the fish’s body under osmotic forces, and salts present in its body will conversely leak out through the wound. All this places an additional burden on the osmotic regulation system, which in severe cases fails to cope, resulting in the fish’s death due to osmoregulatory failure. Danger for most freshwater fish species occurs when pH rises above 9.0 and drops below 5.5.
This condition does not necessarily affect all aquarium inhabitants because different fish species have varying acceptable pH ranges. A sharp pH increase (up to 9-12) can occur in soft-water aquariums with high stocking density, abundant vegetation, and intense lighting. A shift towards alkalinity can also be caused by ammonia input due to elevated organic matter in aquariums.
A major danger to fish life and health arises when transferring them from very mildly acidic and neutral water to alkaline water and vice versa. A rapid (tens of minutes) pH change of 2 units will very likely lead to irreversible gill damage and their gradual destruction. Having experienced such trauma, fish may die, and sometimes this does not happen immediately, but weeks later.
These conditions can be acute, if pH changes occurred rapidly, or chronic, if changes occurred gradually over some time. Acidic or alkaline water irritates the external surface of the fish’s body (including gills), making them easily susceptible to infections and parasites. Alkalosis is less common than acidosis because dissolved minerals that make water more alkaline help stabilize pH.
At the same time, metabolic processes occurring in fish constantly exert an acidifying effect that counteracts the tendency toward rising water alkalinity. It should be noted that ammonia present in water is more toxic at high pH values, while heavy metals in the aquarium are more toxic at low pH values. High carbon dioxide levels in water can lower pH. This often happens in heavily planted aquariums at night when photosynthesis stops and plants release CO2.
Osmotic stress: exposure to water that is either unnaturally rich in minerals or unnaturally deficient in them. Osmotic stress is a disruption of the fish’s osmoregulatory system caused by a large water-permeable area on the skin (e.g., due to injury or disease) or resulting from unsuitable water chemistry. Osmotic stress has more severe consequences for fish species that naturally inhabit mineral-rich waters but are kept in extremely mineral-poor water in the aquarium, significantly increasing the osmotic gradient between the fish and the environment.
Such fish have a less efficient osmoregulatory system than those physiologically adapted to life in mineral-poor water. Therefore, they are unable to cope with the resulting overloads on the osmoregulatory system. Nevertheless, osmotic stress can also occur when fish from mineral-poor waters are kept in overly hard water.
Osmotic shock: a sudden change in dissolved salt concentration and pH – usually observed when fish are transferred from one aquarium to another without acclimatization and preliminary water chemistry testing and adjustment. This leads to fish death within 2-3 days and is often the cause of high mortality among newly acquired fish kept by ignorant or indifferent aquarists. Exposure to high-concentration salt baths (used, for example, to rid fish of external parasites) can also cause severe osmotic shock. An overdose of pH-adjusting products can similarly cause pH shock.
In cases of sharp changes, fish may exhibit typical signs of shock – lying on the bottom on their side, or sometimes even belly-up. However, no signs may be visible until a day or more passes after introducing fish into unsuitable water, but by then, irreparable damage has already been done to the fish’s body. Frequently, on the second or third day, turning on the aquarium light reveals dead fish. All fish reacting negatively to such treatment should be immediately returned to fresh water.
Prevention: fish – especially if wild-caught or only a couple of generations removed from the wild – should be kept in water with a salt content roughly similar to their natural habitat. It must be remembered that dissolved salt concentration is not always determined solely by hardness. Decorative items (such as limestone rocks) can constantly leach soluble minerals into the water. Before moving fish to another aquarium, make sure the pH levels in both tanks match reasonably well (they should not differ by more than 0.5 units). If fish are newly purchased, they can be kept in a quarantine tank while necessary pH adjustments are made gradually.
