If you plan to initiate your own aquaponics system, selecting the appropriate fish species is a crucial decision to accomplish. Fish holds a vital role in an aquaponics setup since it generates organic fertilizers required by plants to flourish.
Choosing the right fish species is crucial for the success of your aquaponics setup as it ensures that the selected fish thrive and survive in your system, despite the wide range of species options available.
What To Consider When Choosing Your Fish
If you intend to create a flourishing aquaponics system, you must be deliberate in choosing fish that can thrive in your area’s weather conditions. Diverse aquatic species require specific pH levels and water temperatures, making it critical to take note of the following considerations when selecting the optimal aquaponics fish for your setup.
When it comes to fish, there are two categories: those that are meant to be eaten and those that are meant for decoration.
When choosing your fish, it’s important to keep in mind their edibility. If you plan on consuming your fish, it’s best to focus on species such as tilapia, catfish, carp, largemouth bass, and others that are safe to eat. However, these kinds of fish can be more difficult to care for and require specific conditions.
It is easier to take care of ornamental fish species such as goldfish and koi, as they have stronger resistance to parasites and diseases, and are relatively cheaper. For indoor aquaponics systems, small species of ornamental fish like angelfish, tetras, and danios are ideal.
The temperature remains the same.
Being cold-blooded species, fish possess limited adaptability to different water temperatures. Certain types of fish flourish better in cold water, whereas others prosper in warm water. Therefore, it is imperative to contemplate whether the fish you intend to cultivate can withstand the temperature range prevalent in your vicinity.
The maintenance of a consistent temperature within the suitable tolerance range is crucial for the well-being and speedy growth of fish, as they flourish in specific temperatures. Familiarity with the temperature fluctuations and the favored temperature ranges of the specific fish species you aim to cultivate will aid in selecting the most fitting fish for your aquaponics setup.
The availability of fish in your area
It is important to take into account the availability of fish in your area. Certain types of fish may only be found in specific regions, such as the Barramundi, which is readily available in Australia but not easily found in the US.
When choosing the ideal fish to rear, the availability of fingerlings is a crucial factor. Tilapia and goldfish are the frequently utilized fish varieties in aquaponics due to their wide accessibility worldwide.
Which species of fish can you lawfully breed in your area?
Some locations have restrictions on the purchase and growth of certain fish. Therefore, it is crucial to verify with your local fish farming regulations to confirm the legality of the fish you plan to utilize in your aquaponics setup.
Maintenance Difficulty and Type of Fish
Certain fish breeds can be raised with minimal effort owing to their sturdiness, while others are more susceptible and require significant investments. Opting for a fish that is resistant to afflictions and parasites is a prudent approach if you desire to keep your setup with minimal attention. Novices venturing into aquaponics can consider Tilapia, Koi, and goldfish as hardy and ideal species.
Requirements regarding size and space.
Your fish tank’s size will dictate the type and number of fish suitable for your setup. Take note of the adult size of the fish you intend to rear, as some need ample space to flourish. To give your fish the appropriate tank size, a channel catfish, for instance, can reach 40-50 lbs and necessitates a 250-plus gallon spacious fish tank.
The capacity of filtration
Your aquaponics system’s ability to filter determines the number of fish that you can accommodate in the tank to maintain equilibrium between the fish’s necessities and the plant’s ability to absorb nutrients. Overpopulation or underpopulation of fish can both be detrimental to their well-being, and overstocking the tank can lead to insufficient oxygen levels in the water. As a general guideline, it is advised to have one inch of fish length per gallon of water in the tank.
Rephrased: Reproduction Patterns
When choosing fish to cultivate in your aquaponics system, their breeding behavior is a crucial consideration. Certain fish varieties are unable to reproduce in confinement, whereas others, such as tilapia, display prolific breeding habits. However, some of these rapidly reproducing fish may pose challenges in inadequately built or limited systems, leading to overstocking issues. To manage this, you may need to house breeding fish in separate tanks to ensure successful spawning and to raise their offspring in a healthy environment.
Diet consisting of fish.
Choosing the right fish diet is crucial when selecting fish for your aquaponics setup. In order to offer the necessary nutrients for plant growth, fish rely on a well-balanced combination of proteins, fats, carbohydrates, vitamins, and minerals. The cost of maintaining your system may be influenced by the type of fish food you choose and the availability of nutrients in the fish food.
It is strongly advised to use commercial feed pellets for small aquaponics setups, particularly in the early stages. While you may opt for alternative or homemade fish food, be diligent in ensuring that the necessary nutritional components are present as they may not be properly balanced.
Water Quality For the Fish
is a commonly used chemical compound that is highly soluble in water and is often used as a refrigerant. One frequently employed chemical compound is ammonia, which possesses high solubility in water and is commonly utilized as a refrigerant.
Fish can be negatively affected by ammonia and nitrite as they are toxic to them. These substances can lead to fish stress and other diseases even if their levels are below 1 mg/liter, although they are considered harmful when exceeding that concentration.
Maintain the same meaning: pH
Fish can tolerate a wide range of pH but thrive at levels of 6.5-8.5. A substantial change in pH levels in a short period can cause problems for the fish.
The oxygen that has been mixed or combined into water to the point of being absorbed or dissolved is referred to as dissolved oxygen.
For the thriving of fish and useful bacteria that change fish excrement into nutrients for plants, it is vital to have Dissolved Oxygen (DO). It is suggested that aquaponics systems ought to keep DO levels at 5ppm or greater. In the case that DO levels are inadequate in your system, enhance aeration by adding air stones or utilizing a larger pump. Furthermore, avoid overstocking fish in your system to prevent low DO levels.
Brightness and Obscurity
The fish tank’s light intensity should be lowered to avoid algae growth. However, it’s important not to make it too dark since sudden exposure to light can cause stress and fear in fish. The preferable option is to allow indirect natural light by using shading. This will help prevent both algae growth and fish stress.
Water Quality in Aquaponics
In order to effectively handle an aquaponics system, growers must have knowledge of fundamental water chemistry to optimize the growth of fish, plants, and bacteria. This write-up will cover the five primary water quality components as well as the critical factors that contribute to the well-being and productivity of fish, plants, and bacteria in an aquaponics system.
Aquaponics Water Quality Parameters
Dissolved Oxygen (DO)
Aquaponics requires dissolved oxygen as a crucial parameter that is essential for the nitrifying bacteria responsible for transforming fish waste into plant nutrients. The optimal DO concentration for aquaponics ranges from 5 ppm or more, and it varies depending on the fish type being cultivated.
For tilapia and catfish, maintaining a DO level of at least 3 ppm is crucial, while rainbow trout requires a minimum of 4 ppm to ensure they stay healthy and grow optimally. It is advisable to monitor the DO levels regularly, especially in new aquaponics systems, as insufficient DO can be harmful to fish. Therefore, daily measurements are recommended to prevent any risks to their well-being.
DO levels can be influenced by various factors.
- Cloudy and rainy days can cause DO to drop because there’s less sunlight for the plants to photosynthesize and produce oxygen.
- Too many fish in the fish tank.
- Too much uneaten food is left in the fish tank.
- Saline water.
There are two methods of measuring dissolved oxygen:
- By using a DO meter.
- The colorimetric approach, where the manganese directly reacts with ethylenediaminetetraacetic acid, gives a pink color and can be read using a color meter.
If fish exhibit symptoms such as diminished appetite, gasping at the surface, congregating near inflow pipes, stunted growth, or heightened vulnerability to diseases, it could be indicative of low levels of oxygen in the water. In the event of observing these indications coupled with decreased dissolved oxygen (DO) levels, it is possible to rectify the situation by augmenting aeration through the addition of more air stones or the utilization of a bigger pump.
pH
In aquaponics systems, pH plays a crucial role in determining the quality of water as it affects various parameters like the ammonia to ammonium ratio and the solubility of nutrients for plant growth. Measured on a scale of 0 to 14, pH stands for “power of hydrogen” and indicates the concentration of hydrogen ions in a solution. The pH scale is categorized into acidic (0-7), neutral (7), and alkaline or basic (7-14) ranges.
A pH range of 6.8 to 7.0 is necessary to ensure both fish and plants thrive in aquaponics. It is therefore imperative to frequently monitor the pH levels of your aquaponics setup to prevent sudden pH fluctuations that could negatively impact the fish, plants, and bacteria, as well as ensure standard aerobic conditions are maintained.
To ensure stability in a new system, it is advisable to conduct pH level measurements on a daily basis. Once the system has achieved stability, pH measurements can be performed less frequently, such as once or twice a week. There are techniques available to regulate the pH in aquaponics, including:
- To raise pH
Combine calcium carbonate and potassium carbonate, adding them in equal quantities simultaneously.
- To Lower pH
To reduce the pH of your system, you have the option of utilizing nitric, phosphoric, or muriatic acids. It is possible to gradually add acid to the system and give it time to evenly spread out before testing again in order to regulate the pH. Keep repeating the procedure until you attain the desired pH.
Water Hardness
The level of calcium (Ca) and magnesium (Mg) in water is measured by its hardness, which is stated in ppm calcium carbonate. Water’s hardness can span from soft (0-75 ppm) to highly hard (>300 ppm), and it is suggested to maintain a water hardness level of 50 to 100 ppm in aquaponics.
Source water’s level of hardness is a critical factor that impacts aquaponics systems’ buffering capacity. Hardness measures the amount of dissolved calcium and magnesium present in the water, and higher levels of dissolved minerals correspond to greater water hardness.
Two different forms of hardness exist: general hardness (GH) and carbonate hardness (KH). GH measures the presence of cations, whereas KH, also called alkalinity, indicates water’s buffering ability. KH affects pH levels by acting as a buffer to decrease them.
The reason for water hardness is the natural existence of minerals and carbonates. Even though hard water contains micronutrients suitable for aquaponics, it does not harm living organisms. Conversely, municipal water exhibits lower hardness and is prone to variations in pH.
Alkalinity
The ability of water to neutralize acids is measured through alkalinity, which can also be referred to as its buffering capacity to combat pH variations. Bicarbonate (HCO3-) and calcium carbonate (CaCO3) are considered bases that contribute to water’s buffering ability. When a water source possesses high levels of these compounds, it can withstand changes in pH. To ensure optimal conditions in aquaponics, alkalinity should remain at 100 ppm.
Ammonia
Aquaponics systems rely heavily on ammonia as it serves as the primary catalyst for kickstarting the nitrogen cycle and driving the ecological processes in the system. Fish generate waste containing high amounts of ammonia which then undergoes bacterial conversion, first into nitrites and then nitrates, which are essential for optimal plant growth.
Ammonia originates from the break down of solid fish waste caused by fish urine and is expelled through their gills. In an aquarium, elevated levels of ammonia can be lethal, however, it is vital as it provides the necessary nutrients to the plants in the system.
The repercussions of ammonia poisoning in aquaponics fish may include:
- Damage to fish tissues, especially in gills and kidneys.
- Physiological imbalance
- Impaired fish growth.
- Weak resistance to diseases.
- Death
Ammonia levels that are excessively elevated.
Ammonia levels increase when the production of ammonia exceeds the capacity of the biofilters. This could result from overfeeding the fish, a high fish population in relation to the water volume, or inadequate aeration.
It is recommended to conduct weekly checks on the ammonia levels of your aquaponics system, even if it appears to be running smoothly. This allows for early detection of any changes and the opportunity to make necessary adjustments before they turn into a problem. The following approaches can be used to regulate ammonia levels in aquaponics systems.
Decreasing the Ammonia Levels can be Achieved by:
- Checking the pumps and DO levels.
- Adjusting fish feeding rates or the fish density (A rule of thumb is per 2 gallons of water, 1lb of fish).
- Increasing nitrification efficiency.
- Reducing the quantity of nitrogen going into your system by lowering feeding rates, removing dead fish, and removing uneaten fish feed after feeding.
Ammonia levels are too low.
Insufficient ammonia in your system will hinder plant growth, thus producing and converting enough ammonia into nitrate is vital for healthy plant growth. Scarcity of ammonia can be attributed to a dearth of fish in the system or excessive water volume in relation to the fish stock. To address low ammonia levels, options include adding more fish, augmenting feeding rates, or utilizing a smaller tank.
Water Temperature
The aquaponics system’s water temperature affects the fish species that can be raised, plant growth, and the biofilter’s efficiency. Fish species have temperature requirements, with warm-water species like goldfish, catfish, and tilapia preferring temperatures between 65°F to 85°F, and cold-water species like trout thriving in temperatures between 55°F to 65°F. Moreover, water temperature influences the water’s oxygen level, making it crucial to monitor the temperature regularly.
