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Many people who are new to keeping discus assume that since the water parameters (Ph, TDS, ammonia, nitrite, and nitrate) are all normal, and the water appears crystal clear, they make the mistake of thinking that the water is healthy. It may be for some other types of fish, but not discus unless the water is also biologically clean. How to keep the water biologically clean, and why this is critical for healthy discus is the purpose of this post.
Assuming that the tank has a well established bio-filter (which maintains ammonia, and nitrite levels at zero), the next most important water quality consideration is bioload and biomass resulting from food fed to the fish. Food contains organic compounds that are not toxic to the fish, however two undesirable affects result. First, there are bacteria that feed on the organic compounds and this results in other compounds that are toxic. This process is called decomposition and is very common in nature as evident by the foul smell of a dead animal or decaying vegetation. Second, pathogens (bacteria, viruses, and parasites) feed on the organic compounds and this permits them to multiply greatly. Note that there are many different types of bacteria in the tank, some are beneficial and some are not.
The recommendations I give in this post are mine alone. In some instances there is considerable differences on the SD Forum as to what these recommendations should be.
What Is Bioload and Biomass and How To Control Them
Bioload and biomass are affected greatly by the type of food and how it is fed to the fish. Food such as beef heart mix and unrinsed blood worms (and others) contribute more organic compounds than freeze dried or flake foods. When feeding the fish, do not overfeed and feed them more often with a little at a time, so that more of the food is actually eaten by the fish.
Bioload and biomass both result from food placed in the tank. The fish eat a portion of the food and the remaining part either falls to the bottom of the tank, or becomes suspended or dissolved in the water column. The portion eaten by the fish is partly decomposed by the digestive tract of the fish and is eliminited as feces. The bioload/biomass exists in several forms: uneaten food and feces, suspended/dissolved organic material in the water column, food and feces existing in the substrate, and food that collects on all surfaces in the tank. These are controlled by water changes or by syphoning material from the tank bottom.
Uneaten Food and Feces-- Feces contains food that is not completely decomposed and this usually collects with uneaten food on the bottom of the tank. If this material is neglected, it will collect into a very large biomass which will permit pathogens to multiply greatly as they feed on it. As further decomposition takes place, other undesirable compounds will be produced, and these will remain at the bottom or become suspended in the water column. The fish will ingest some of these pathogens when they feed at the bottom. Control of this is accomplished with tank maintenance by syphoning the bottom and this should be done on a regular basis. For adult discus, my recommendation is no less than twice a week. Juveniles require more frequent cleaning.
Suspended or Dissolved Organic Compounds-- These organic compounds exist in the water column as bioload. They originate from uneaten food and feces containing partially decomposed food, which is suspended or dissolved in the water column. Some of these organic compounds decompose in the water column. Water circulation transports this bioload to the substrate (it one exists) and to all other surfaces with in the tank including the walls, bottom, and anything else in the tank. Control of these organic compounds in the water column is accomplished with water exchange. My recommendation is not less than 30% daily for adults and greater amounts for juveniles.
Gravel or Sand Substrate-- Uneaten food and feces becomes trapped in gravel and this can accumulate into a huge biomass, even if one attempts to clean it regularly. Thats because much of the organic material will stick to the gravel thus making it impossible to remove it without also removing the gravel. Aslo, water circulation can be blocked in the gravel thus depriving the flow of oxygen which will stop the process of decomposition and this can result in even bigger problems. Thus my recommendation is to avoid gravel substrate completely. Sand is a better substrate than gravel because feces and food are less likely to become trapped. However the sand at the top still collects a biomass because food suspended in the water column will stick to the sand particles at the top and thus collect to form a biomass. This biomass will remain in the tank unless the sand is also removed. For these reasons, my recommendation is to go with a bare bottom tank, especially for anyone just beginning. A bare bottom tank is not only much cleaner, but also much easier to clean.
Food Collecting on All Surfaces in the Tank-- Another form of biomass occurs when suspended organic material in the water column collects on everything in the tank including walls, bottom, decorative items (artificial plants, rocks, etc..) and everything else in the tank. This form of biomass is different than gravel substrate because water circulation is available to allow the organic material to decompose. Control of this biomass is accomplished by removing the decorative items and cleaning them outside the tank, and then wiping the sides and bottom of the tank clean. This loosens the biomass and places it in suspension where water changes remove it from the tank. A pretty good test for assessing this biomass on decorative items is what I call the "sniff" test. Remove the item from the tank and place it close to the nose, a biomass will exhibit a foul odor. This test can be used as a pretty good indication of how often it should be cleaned. My recommendation for cleaning decorative items is to place them in a bucket and add a 8 to 1 mixture of water and hydrogen peroxide (3%). Hydrogen peroxide can be purchased in the Wal-mart pharmacy for under $1 per quart. It is non toxic and can be rinsed off after letting it set overnight in the bucket. Does a wonderful job of removing algae. My recommendation is to clean this form of biomass not less ten days for adult discus, and more often for juveniles.
Why Discus Require Biologically Clean Water
Many of the strains of discus available today have evolved in water with a low Ph for thousands of years. As such their immune systems have adapted to the quantity and types of pathogens (bacteria, viruses, and parasites) that are common to their native habitat. It turns out that water with higher Ph has not only many more pathogens, but also a different type. Thus the fish are much more sensitive to attack from unfamiliar pathogens. Young discus are especially vulnerable because the immune system adapts somewhat as they age. This is a very serious problem to the extent that many discus keepers recommend that fish from different suppliers should not be mixed due to the possibility that bacteria from one supplier will be harmful to discus from a different supplier, even though they are not harmful to the first.
Another important consideration results because discus are quite sensitive and become easily stressed. Stress can be caused by changes in water parameters (Ph, TDS, ammonia, nitrite, and nitrate), temperature, lighting, motion outside the tank, pecking order, and other factors. Water that is not biologically clean also causes stress. In fact, whenever I notice that my fish are not acting normal, the first thing I do is to suspect something wrong with the water and immediately make a water change. The amount of aggression occurring between the fish can also be a sign of stress. My experience has shown that when I get all of the tank conditions correct and stabilized, that the aggression due to the pecking order is greatly reduced. When discus become stressed, they often become lethargic and refuse to eat. When this happens, their immune system becomes weakened and they are much more subject to attack from pathogens.
Assuming that the tank has a well established bio-filter (which maintains ammonia, and nitrite levels at zero), the next most important water quality consideration is bioload and biomass resulting from food fed to the fish. Food contains organic compounds that are not toxic to the fish, however two undesirable affects result. First, there are bacteria that feed on the organic compounds and this results in other compounds that are toxic. This process is called decomposition and is very common in nature as evident by the foul smell of a dead animal or decaying vegetation. Second, pathogens (bacteria, viruses, and parasites) feed on the organic compounds and this permits them to multiply greatly. Note that there are many different types of bacteria in the tank, some are beneficial and some are not.
The recommendations I give in this post are mine alone. In some instances there is considerable differences on the SD Forum as to what these recommendations should be.
What Is Bioload and Biomass and How To Control Them
Bioload and biomass are affected greatly by the type of food and how it is fed to the fish. Food such as beef heart mix and unrinsed blood worms (and others) contribute more organic compounds than freeze dried or flake foods. When feeding the fish, do not overfeed and feed them more often with a little at a time, so that more of the food is actually eaten by the fish.
Bioload and biomass both result from food placed in the tank. The fish eat a portion of the food and the remaining part either falls to the bottom of the tank, or becomes suspended or dissolved in the water column. The portion eaten by the fish is partly decomposed by the digestive tract of the fish and is eliminited as feces. The bioload/biomass exists in several forms: uneaten food and feces, suspended/dissolved organic material in the water column, food and feces existing in the substrate, and food that collects on all surfaces in the tank. These are controlled by water changes or by syphoning material from the tank bottom.
Uneaten Food and Feces-- Feces contains food that is not completely decomposed and this usually collects with uneaten food on the bottom of the tank. If this material is neglected, it will collect into a very large biomass which will permit pathogens to multiply greatly as they feed on it. As further decomposition takes place, other undesirable compounds will be produced, and these will remain at the bottom or become suspended in the water column. The fish will ingest some of these pathogens when they feed at the bottom. Control of this is accomplished with tank maintenance by syphoning the bottom and this should be done on a regular basis. For adult discus, my recommendation is no less than twice a week. Juveniles require more frequent cleaning.
Suspended or Dissolved Organic Compounds-- These organic compounds exist in the water column as bioload. They originate from uneaten food and feces containing partially decomposed food, which is suspended or dissolved in the water column. Some of these organic compounds decompose in the water column. Water circulation transports this bioload to the substrate (it one exists) and to all other surfaces with in the tank including the walls, bottom, and anything else in the tank. Control of these organic compounds in the water column is accomplished with water exchange. My recommendation is not less than 30% daily for adults and greater amounts for juveniles.
Gravel or Sand Substrate-- Uneaten food and feces becomes trapped in gravel and this can accumulate into a huge biomass, even if one attempts to clean it regularly. Thats because much of the organic material will stick to the gravel thus making it impossible to remove it without also removing the gravel. Aslo, water circulation can be blocked in the gravel thus depriving the flow of oxygen which will stop the process of decomposition and this can result in even bigger problems. Thus my recommendation is to avoid gravel substrate completely. Sand is a better substrate than gravel because feces and food are less likely to become trapped. However the sand at the top still collects a biomass because food suspended in the water column will stick to the sand particles at the top and thus collect to form a biomass. This biomass will remain in the tank unless the sand is also removed. For these reasons, my recommendation is to go with a bare bottom tank, especially for anyone just beginning. A bare bottom tank is not only much cleaner, but also much easier to clean.
Food Collecting on All Surfaces in the Tank-- Another form of biomass occurs when suspended organic material in the water column collects on everything in the tank including walls, bottom, decorative items (artificial plants, rocks, etc..) and everything else in the tank. This form of biomass is different than gravel substrate because water circulation is available to allow the organic material to decompose. Control of this biomass is accomplished by removing the decorative items and cleaning them outside the tank, and then wiping the sides and bottom of the tank clean. This loosens the biomass and places it in suspension where water changes remove it from the tank. A pretty good test for assessing this biomass on decorative items is what I call the "sniff" test. Remove the item from the tank and place it close to the nose, a biomass will exhibit a foul odor. This test can be used as a pretty good indication of how often it should be cleaned. My recommendation for cleaning decorative items is to place them in a bucket and add a 8 to 1 mixture of water and hydrogen peroxide (3%). Hydrogen peroxide can be purchased in the Wal-mart pharmacy for under $1 per quart. It is non toxic and can be rinsed off after letting it set overnight in the bucket. Does a wonderful job of removing algae. My recommendation is to clean this form of biomass not less ten days for adult discus, and more often for juveniles.
Why Discus Require Biologically Clean Water
Many of the strains of discus available today have evolved in water with a low Ph for thousands of years. As such their immune systems have adapted to the quantity and types of pathogens (bacteria, viruses, and parasites) that are common to their native habitat. It turns out that water with higher Ph has not only many more pathogens, but also a different type. Thus the fish are much more sensitive to attack from unfamiliar pathogens. Young discus are especially vulnerable because the immune system adapts somewhat as they age. This is a very serious problem to the extent that many discus keepers recommend that fish from different suppliers should not be mixed due to the possibility that bacteria from one supplier will be harmful to discus from a different supplier, even though they are not harmful to the first.
Another important consideration results because discus are quite sensitive and become easily stressed. Stress can be caused by changes in water parameters (Ph, TDS, ammonia, nitrite, and nitrate), temperature, lighting, motion outside the tank, pecking order, and other factors. Water that is not biologically clean also causes stress. In fact, whenever I notice that my fish are not acting normal, the first thing I do is to suspect something wrong with the water and immediately make a water change. The amount of aggression occurring between the fish can also be a sign of stress. My experience has shown that when I get all of the tank conditions correct and stabilized, that the aggression due to the pecking order is greatly reduced. When discus become stressed, they often become lethargic and refuse to eat. When this happens, their immune system becomes weakened and they are much more subject to attack from pathogens.
This is extremely informative to the beginner. This takes on another level of consideration for my tank. It makes me wonder if I've been doing this all wrong. I am curious about what some of the other seasoned hobbyists think of this post.
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