Introduction to Aquaponics
Healthy Fish Environment
It is really important to understand
that each variety of plant and fish have their own specific optimum conditions,
so Aquaponics is about finding a balance
for the fish, plants and bacteria.
The main factors that will contribute to healthy fish are:
The main factors that will contribute to healthy fish are:
- Temperature
- Water quality (pH & Ammonia)
- Food.
Temperature
Each species of fish will have an ideal temperature range and an optimum temperature within this. This optimum temperature may not always be met as it can conflict with the temperature range of the plants or the bacteria. However, a compromise can be reached, in general, at 23° C. Outdoor systems will usually however be lower than this.
Any major changes in temperature can have adverse effects on fish health, particularly when reaching extremes of temperatures during the day and night cycle. It is important to know the optimum range of the fish you are growing, as some fish will stop feeding at a certain temperature, and some will suffer from thermal stress and may die. For example, some Tilapia will stop feeding at 18° C and can perish below 12° C.
When adding water or topping up (replenishing the water lost through evaporation), it is important to do this slowly to afford the fish a chance to adjust to the temperature change. When adding the fish to the water initially, it is important to let the fish acclimatize to the new conditions and temperature.
Be aware of the year round temperature in the local area and select a fish that will thrive in all seasons. It can be expensive to use cooling or heating equipment, and this may be unnecessary if the fish are selected properly. Using insulation and covering the reservoir (fish tank) will help to stabilize the temperature. Be aware that higher the temperature, the lower the in the water: this will have a negative impact on the fish, bacteria and plants.
Any major changes in temperature can have adverse effects on fish health, particularly when reaching extremes of temperatures during the day and night cycle. It is important to know the optimum range of the fish you are growing, as some fish will stop feeding at a certain temperature, and some will suffer from thermal stress and may die. For example, some Tilapia will stop feeding at 18° C and can perish below 12° C.
When adding water or topping up (replenishing the water lost through evaporation), it is important to do this slowly to afford the fish a chance to adjust to the temperature change. When adding the fish to the water initially, it is important to let the fish acclimatize to the new conditions and temperature.
Be aware of the year round temperature in the local area and select a fish that will thrive in all seasons. It can be expensive to use cooling or heating equipment, and this may be unnecessary if the fish are selected properly. Using insulation and covering the reservoir (fish tank) will help to stabilize the temperature. Be aware that higher the temperature, the lower the in the water: this will have a negative impact on the fish, bacteria and plants.
pH
A key factor is the water measurement of how acidic or alkaline a solution is this is referred to as its pH.
In Aquaponics systems a balance is found at around 6.5 - 7.5 pH, where both organisms will continue to grow and mutually benefit each other.
The pH range for fish is higher than the range of pH for plants but close to that of the bacteria. The balanced pH range in an Aquaponics system is 6.5 – 7.5.
The ideal pH will also depend on the specific species being used in the Aquaponics system. Any extremes of pH or major swings (more than 0.3 over a few hours) will have a negative impact on fish health, and can cause stress or even death. If the fish are stressed they will be more susceptible to disease or death. Most freshwater fish will do well in a pH range of 6.0 – 8.5. Fish will adjust to different pH ranges, but only if done very slowly.
In Aquaponics the plants will produce some oxygen through photosynthesis during the day but they will produce carbon dioxide at night. The carbon dioxide will lower the pH hence pH may be lower in the morning than the afternoon.
- Most fish prefer a pH range of 7- 9 pH which is alkaline.
- Most plants prefer a pH of around 4-7 pH which is more acidic.
In Aquaponics systems a balance is found at around 6.5 - 7.5 pH, where both organisms will continue to grow and mutually benefit each other.
The pH range for fish is higher than the range of pH for plants but close to that of the bacteria. The balanced pH range in an Aquaponics system is 6.5 – 7.5.
The ideal pH will also depend on the specific species being used in the Aquaponics system. Any extremes of pH or major swings (more than 0.3 over a few hours) will have a negative impact on fish health, and can cause stress or even death. If the fish are stressed they will be more susceptible to disease or death. Most freshwater fish will do well in a pH range of 6.0 – 8.5. Fish will adjust to different pH ranges, but only if done very slowly.
In Aquaponics the plants will produce some oxygen through photosynthesis during the day but they will produce carbon dioxide at night. The carbon dioxide will lower the pH hence pH may be lower in the morning than the afternoon.
Ammonia
The ammonia, nitrite and nitrate are fundamental compounds of the Nitrogen cycle and therefore fundamental to Aquaponics.
Of the components, the fish are the most sensitive organism to the levels of these compounds, thus fish dictate the ‘safe’ levels within the Aquaponics system. Ammonia is toxic to fish; anything over 0.25 ppm (parts per million) can be harmful and cause stress, which can leave the fish more susceptible to disease. Nitrate will also be harmful at 0.5 ppm or higher. Nitrates should be kept at 20 ppm or lower although on a short-term basis they can be higher. Ammonia poisoning is known to cause extensive tissue damage, in particular the gills and kidney, physiological imbalances, decreased resistance to disease, impaired growth and even death. It can be seen physically by reddening of the eyes. Nitrite poisoning inhibits the uptake of oxygen by red blood cells also known as brown blood disease. |
Feeding
Fish feed is one of the main inputs within an Aquaponics system. The content of the fish feed is the main source of protein and nutrients for the fish and eventually the nutrients for the plants. We recommend using a commercial organic feed with a high protein source or an organic alternative feed source.
One of the most common problems in any Aquaponics system is over feeding. This is when the fish cannot eat the amount of feed given to them. This will result in cloudy water, excess ammonia and fish health problems. We recommend simply feeding them a set amount, and after 30 minutes if food is left uneaten, remove it and reduce the feed amount the next day. It may be more beneficial to feed smaller amounts twice daily. If the ammonia levels are rising or ‘spiking’ it will be necessary to stop feeding for a day or two in order to allow the system to stabilize. Then simply resume feeding at a lower rate.
Fish feed will depend on the focus of the Aquaponics system, whether that is plants or fish. We recommend that in starting off in Aquaponics, the focus should be on the vegetable production rather then fish. Higher filtration and more space is needed for intensively growing fish. Fish feed charts are available online for the specific fish being grown. Regular fish pellets are ideal for fish feed although alternate feed sources will be discussed in a later article.
Feed conversion ratio (FCR) refers to the amount of food eaten by the fish relative to the overall poundage of meat produced. Protein is the most important aspect of fish feed. It provides energy and supplies amino acids (Amino acids are the building blocks of protein in the fish’s cells). Protein requirements are generally higher in smaller fish. As fish grow larger, their protein requirements usually decrease. Fish are capable of using a high protein diet, but as much as 65% of the protein may be lost to the environment. Recommend is a fish feed with a protein content of 25 – 40% for edible fish, decorative fish will have lower protein requirements.
One of the most common problems in any Aquaponics system is over feeding. This is when the fish cannot eat the amount of feed given to them. This will result in cloudy water, excess ammonia and fish health problems. We recommend simply feeding them a set amount, and after 30 minutes if food is left uneaten, remove it and reduce the feed amount the next day. It may be more beneficial to feed smaller amounts twice daily. If the ammonia levels are rising or ‘spiking’ it will be necessary to stop feeding for a day or two in order to allow the system to stabilize. Then simply resume feeding at a lower rate.
Fish feed will depend on the focus of the Aquaponics system, whether that is plants or fish. We recommend that in starting off in Aquaponics, the focus should be on the vegetable production rather then fish. Higher filtration and more space is needed for intensively growing fish. Fish feed charts are available online for the specific fish being grown. Regular fish pellets are ideal for fish feed although alternate feed sources will be discussed in a later article.
Feed conversion ratio (FCR) refers to the amount of food eaten by the fish relative to the overall poundage of meat produced. Protein is the most important aspect of fish feed. It provides energy and supplies amino acids (Amino acids are the building blocks of protein in the fish’s cells). Protein requirements are generally higher in smaller fish. As fish grow larger, their protein requirements usually decrease. Fish are capable of using a high protein diet, but as much as 65% of the protein may be lost to the environment. Recommend is a fish feed with a protein content of 25 – 40% for edible fish, decorative fish will have lower protein requirements.