Basics of Aquaponics Fish, Grow Bed and Profit

Aquaponics Grow Bed

The aquaponics grow bed is one of the two main components of an Aquaponics farming system, the other being the fish tank. The grow bed houses the plants and the bacteria responsible for breaking down the fish waste and turning them into nutrients for the plants.
In an aquaponics system, water is pumped from the fish tank and into the grow bed. Bacteria break down fish waste into nitrogen, which is taken up by the plants and used to grow. The clean water is then returned into the fish tank. Through this process, an Aquaponics system uses just 10% of the water that traditional agriculture requires.


With regards to the ratio of grow bed to the fish tank, here’s how you can calculate it. Fish density should be kept at no more than 1 pound of fish per 3 gallons of water. Now, for every 6 gallons of water, you should have about 1 square foot of deep grow bed (about 12 inches deep). This is to ensure an adequate fish waste to plant biomass ratio. Therefore, you will be having about 2 pounds of fish for each square foot of deep grow bed area. However, note that this is a maximum number. If you are just starting out, it is safer to opt for one fish per 5 to 10 gallons of water. As a rule of thumb, use a fish tank to grow bed ratio of 1:1 (by volume).
It is safer to have a higher grow bed: fish tank ratio than the other way round. If you have too little grow bed, there won’t be enough bacteria to break down the fish wastes as they accumulate, and soon enough the fish and plants will start dying. You should use a grow bed that is about 12 inches deep and definitely nothing less than 9 inches.
When setting up your system, the water level in the grow bed should be about 1 inch from the top, as the top of the plants should not be wet. In addition, this will ensure that there is no direct sunlight on the water, which would, in turn, cause an algae bloom. Therefore with a 12 inch deep grow bed, you will be looking at about 10 to 11 inches of which are submerged.
An important aspect of a healthy grow bed is dissolved oxygen, as oxygen is essential for proper bacteria (and fish) growth. Plants also require good oxygen levels on their roots. Ideal dissolved oxygen levels for an aquaponics system are those above 6 parts per million. To ensure healthy dissolved oxygen levels, you should incorporate water stone aeration and some water jetting action; you can incorporate the latter in the way the water returns back to the fish tank from the grow beds.

Aquaponics Grow Bed Media and Water

Aquaponics Grow Bed

Aquaponics grow bed media and water, two crucial components of an aquaponics system. The grow bed medium is the plant’s habitat while the water is the fish’s habitat. The two are interconnected and if there are problems in one, they will manifest themselves in the other.
There are many grow bed media to choose from, ranging from simple ones to ‘bioengineered” branded ones. A very popular and effective one is gravel, which also happens to be very cheap. Gravel is ideal because it provides good support for the roots of the plants and filters the water well. In addition, it proves to be a good habitat for the beneficial bacteria, which will be busy turning fish wastes into plant nutrients. Get round gravel, and it should be big enough not to clog but small enough to provide good root support. The plant roots need good water circulation and oxygen, and if the medium compacts too much, this won’t be possible. Good medium size for Aquaponics is around 0.5 to 0.75 of an inch in diameter.
If you opt for another type of medium, you need to ensure that it has some important properties. It should be chemically inert and it must not influence the pH of the water. For example, limestone leaks calcium carbonate and this will push the pH up. Gravel, lava rock, and most river stones are pH neutral. Similarly, the medium should not decompose, as this will affect the pH levels and potentially clog the systems. Decomposing materials can also leak substances in the water that can harm you fish. Avoid soil, peat moss, sawdust or wood chippings.


It is important that the medium you choose is porous, as this will allow for good air and water circulation and will give the bacteria plenty of surface area to colonize. You should also make sure that the medium is easy to handle; it should be gentle on the hands and on the plant’s roots.
Now, something about the water. You want the water to be pure, free of chlorine and other chemicals and as close to pH 7 as possible. Municipal water will be of high pH and will contain chlorine. However, all you have to do is to fill your tank and let it sit for two or three days. The chlorine will evaporate off by itself. If the pH of your water is too high, you can buy aquarium pH regulators, or else add in some vinegar or iron sulfate fertilizer. Add small quantities at a time and test. On the other hand, if the pH of the water is too low, get an aquarium pH regulator, add in some baking soda or calcium carbonate. Again, add in small quantities at a time and test. You final pH should be between 6.7 to 7.

Aquaponics Fish

Aquaponics Grow Bed_Fish_Profit

The aquaponics fish in your system not only provide you with tasty food (rich in protein and omega 3s) but also provide nutrients for the aquaponics vegetables that you’re growing. Growing fish yourself will save you lots of money and you will have peace of mind knowing that the fish you’re eating are free from toxic metals and petroleum residues, which is becoming a growing problem with sea-caught fish nowadays. You can also make a great income selling aquaponics fish, because the expenses involved in growing them are very small.
So, which fish species do you choose for your aquaponics farming system? There are a few things you have to keep in mind before making your decision. Each species will have it s own different requirements and optimal temperature and pH ranges. In addition, some species will be able to grow in a large population density (more fish in less space) while others may need more space. Different fish also grow at different rates; presumably you want ones which grow fast.
Two very popular fish for aquaponics systems are tilapia and trout. If you live in warmer areas, you should opt for tilapia. They grow best at temperatures of 82° to 86°F and start dying if the temperature drops below 50°F. This is because at temperatures below 54°F, tilapia lose their resistance to disease and are prone to infections. Of course, if you live in cold areas but keep your house heated, you can set up the aquaponics system in a room and still grow tilapia. Tilapias are particularly suited to aquaponics farming because they are very hardy and will survive fluctuations of pH and waste build-up better than most other fish. In addition, they can grow well in crowded tanks, and grow quickly.
Another excellent aquaponics fish for warm climates is the catfish, which grows best at a temperature of around 80°F. They are very resistant to disease and parasites, but are sensitive to oxygen levels. If you grow catfish, make sure you have a good aerating system in place and carry regular tests.
If you live in colder areas, you should opt for trout. Although different trout species have slightly different requirements, most have an optimal range of 40° to 65°F. Like tilapia, they grow fairly quickly and make tasty food.
Some aquaponics farmers also grow goldfish. Now, although these are not used for food, they can be easily sold to pet-shops to be resold as pets. Goldfish are very hardy, grow in a variety of conditions and can fetch a significant profit. You can also sell goldfish directly by placing ads in local newspapers.

Aquaponics For Profit

Many people start this venture as a hobby, and quickly turn to doing aquaponics for profit, because they immediately realize how profitable it can be! It can be set up with minimum start up costs, and running costs are very low. With its unique set up, the system practically runs itself, as the plants and fish form a symbiotic relationship with the help of bacteria; the latter turn fish waste into plant nutrients, cleaning the water for the fish and providing fertilizer for the plants.
Aquaponics is rapidly gaining popularity because of the rising prices of food and the increasing demand for organic food (which is what you’ll be growing with an aquaponics system). Running an Aquaponics for profit business has many advantages. It is ideal for those who do not have a lot of money to invest, as it requires minimum costs to set up and run. As the costs are low, the profit margin is very significant. Both organic vegetables and fish fetch very good prices!
Another advantage of an Aquaponics for profit business is that it requires minimal space – Aquaponics is in fact the most space-effective method of food production. Generally, a room or garage is more than enough to produce enough food to make a profit.
Aquaponics is also fairly flexible, in the sense that you can grow many different species of plants and fish. So you may grow different species at different times of the year according to demand and competition in your area. For example some people grow predominantly vegetables, while others opt to growing herbs. Of course, there is no reason why you can’t grow both! The same goes for fish; there are many species you can rear. In addition, instead of growing fish for food, some people grow goldfish and other aquarium fish species which then they sell to pet shops or directly to owners. With some aquarium fish species, the prices fetched can be much higher than the prices for most ‘food’ fish. To keep the costs down, you should choose fish which have temperature requirements that are similar to the average temperature in your area. This will save you from using electricity to heat the water.
Popular fish which are grown using aquaponics for profit include tilapia (mainly in warmer climates), trout (mainly in colder climates), catfish, koi, bluegill, smallmouth bass, and goldfish (to be sold as pets). Make sure to check your state laws first, as there are some limitations on which fish can be grown. With regards to plants grown successfully in Aquaponics systems for profit, excellent examples include cucumbers, tomatoes, melons, strawberries, lettuce, spinach, peas, beans and squash; and herbs such as as rosemary and basil.