Aquaculture....

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Aquaculture, or Aquaponics is simply the combination of aquaculture (fish farming) and hydroponics (growing plants without soil). In a symbiotic relationship, the fish provide nutrients necessary for plant growth. And the plants, in taking up the nutrients, help to clean the water the fish live in. An aquaponic system is a mini ecosystem where both plants and fish can thrive.

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[The Cell]

Tips for the Beginning AquaCulturist

By Myles Harston
As Seen in Aquaponics Journal April/May 1998

Aquaculture, the culturing of fish and aquatic plants, is currently the fastest growing segment of the agricultural industry. Indoor aquaculture has become increasingly popular for many reasons. Some of those include:

1. It allows farmers to raise fish closer to the marketplace reducing transportation costs.
2. Aquaculture enables farmers to fill niche markets with specialty items.
3. Fish farming helps to fill the need for products that are free of pollutants and are an effective solution to over-fishing. (See National Geographic November 1995).

In all recirculating aquaculture systems there are five basic components:

1. The culture tank where the aquatic animals are kept.
2. Temperature regulation.
3. Dissolved oxygen supplementation.
4. Fecal/particle filtration.
5. Bio-filtration where the ammonia produced by the fish is broken down, with the help of useful aerobic bacteria, into nitrites and then nitrates.

Although there are many variations of these five components, the elimination of any one of these would be impractical.

Prior to beginning your aquaculture enterprise you should check with your state agriculture agencies to find out what permits are required. Some states are more restrictive than others, particularly with regard to certain non-native species.

Water Quality

For your operation you should consider not only the amount of water you have available but the quality of the water itself. The water should be free from chemicals that are harmful to the species you plan to raise. I have found naturally existing amounts of ammonia in some areas high enough to kill almost any kind of aquatic life.

Waste water management and the disposal is a very important consideration. Since waste water from aquaculture is ideally suited for feeding a wide variety of leafy plants, aquaponics is an excellent option for getting rid of it. If it is not used in aquaponics you will need to have some other means of disposal.

You should also reasearch the tolerances of your selected species as to the critical water quality parameters. These upper limits are often debated and may vary depending on your water and the management of your system, but should serve as a guide when starting out.

The most common water quality parameters which should be monitored are: dissolved oxygen, ammonia, nitrites, pH, hardness, alkalinity, and carbon dioxide.

Feed

Fish feed is one of the most important considerations because feed costs will be about 1/3 of your total operating expenses. There are many different types of commercial feeds available.

Floating pellets of various sizes are usually preferred for juvenile and adult fish. When you have new born fry, they will thrive on brine shrimp and ground up commercial food prepared in gelatin.

Food should be stored in a cool, dry place for no more than 3 months in advance of using, because crucial vitamins (especially vitamin C) are lost with age. Refrigeration or freezing can extend the shelf life of the feed.

Optimum feeding rates should be about 3% of the fishes body weight per day (fry may exceed this ratio). You should catch random specimens periodically to help calculate the percentage of feed to be fed daily.

Care should be taken not to over feed more than the fish can consume at ony one time. Excessive feeding will quickly foul the water and can cause unbalances in your bio-filter's stability.

Bio-Filtration

Bio-filters utilize two kinds of beneficial bacteria: Nitrosomonas and Nitrobacter. The bacteria are living organisms which utilize oxygen and consume food, ammonia, and nitrites. Ammonia production is proportional to the feeding rate, therefore, the capacity of a bio-filter should be sized-based on the maximum weight of the fish and the highest rate you will fee.

In your initial setup of the bio-filter, it is wise to use a commercially available bacteria seed culture. When we begin to seed our system, we trickle in the recommended amount over several days rather than all at once. We continue to trickle small amounts into the water until the ammonia and the nitrites come down to acceptable levels. Let your test kits be your guide.

pH

As the poundage of fish in your tank increases and the bio-filter becomes more efficient, the pH will start to drop. This is caused by the bacteria producing acid and is normal.

When we are just raising fish we try to maintain our culture water at a pH of about 7.4. To raise the pH we simply use sodium bicarbonate (baking soda), which can be found in a local feed store in 50 pound bags for about $15.00.

If you need to lower your pH, sulfuric acid can be used. You should monitor your pH regularly. When adjustments need to be made, do it in small increments so as not to shock the fish.

When we combine fish culture with growing plants (aquaponics), we must compromise with the needs of both the plants and the fish and maintain a pH of about 6.8. To raise the pH when doing Aquaponics, unless it is an emergency don't add sodium bicarbonate to the water, it will harm the plants. You can use either potasium carbonate or calcium carbonate.

We have found that when we allow the pH to drop much lower than 6.7 denitrification is less efficient.

Summary

If you are just now looking to get your feet wet in aquaculture, it's always a good idea to start with a smaller system (under 2,000 gallons) so you can learn how to monitor and control your water parameters.

I recommend investing in quality test kits and using them regularly. Happy Fishing!







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[The Cell]

AquaRanch Fisheries


What to Know Before Starting

* Permits
* Water Management
* Bio-Filters
* Fish Food
* Optimal Feeding Rates
* Introducing Fish to Your System
* Marketing Your Fish
* Bacteria
* Cleaning The Fecal/ParticleClarifier

Permits
tilapia In order to engage in aquaculture practices, you may be required by your state law to possess either permits or licenses. Some states also require inspections for certain species. Contact your state extension office for information on the requirements for your state.

Water Management
Before starting your system, you should consider all aspects of water management in the facility. For the operation, an ample supply of good quality water is necessary. This water must be easily accessible and free from excess chemicals that may harm fish. Water should be assayed for the following: nitrates, nitrites, ammonia, chlorine, chloramine, hardness, pH, alkalinity, dissolved gases, and heavy metals.

Waste water management is a very important aspect to consider during the initial assessment of the aquaculture facility. You will have considerable amounts of water that will need to be disposed of properly. The waste water is ideal for growing greenhouse plants or fertilizing a lawn or garden. New research in Aquaponics has shown that there are many plants that thrive on aquaculture water.

You should also research the upper tolerances of your selected species as to the critical water quality parameters. These upper limits are often debated, and may vary with different water and management. You need to discuss these variables with your aquaculture advisor. The most common water quality parameters which should be considered are: dissolved oxygen, ammonia, nitrites, pH, hardness, alkalinity, and carbon dioxide.



Bio-Filters
Bio-Filters utilize two kinds of beneficial bacteria called Nitrosomonas and Nitrobacter to convert toxic ammonia and nitrite to the less toxic nitrate. The Bio-Filter is similar to a living organism that eats and breathes. The need for ammonia reduction in a recirculating system is essential, as the presence of even sub lethal amounts of unionized ammonia can cause severe damage to fish. Ammonia production is proportional to the feeding rate, therefore, the capacity of our Bio-Filter is sized to both the maximum weight of fish and the highest rate at which you should feed. The amount of surface area and water exchange rate are two major factors that limit the capacity of a Bio-Filter. In the initial setup of the system, it is wise to seed the Bio-Filter with a commercially available bacteria seed culture. During operation of your system, it is crucial to monitor the efficiency of your Bio-Filter. The level of both ammonia and nitrites show the efficiency of your Bio-Filter bacteria populations. Care must be taken to monitor for the possibility of a bacteria population crash. In the event of a Bio-Filter crash, we have found several steps that may help you in this crisis. We reduce the amount we are feeding, lower the temperature by about 10 degrees and then add about 4 pounds of pure salt per 100 gallons of water and then re-seed the Bio-Filter. It could take a few weeks to gradually bring everything back to normal.

As the poundage of fish increases and the Bio-Filter becomes more efficient, the pH will start to drop, sometimes rather quickly. When this occurs, It will be necessary to add calcium hydroxide, potassium hydroxide or sodium bicarbonate (baking soda) in order to raise and stabilize the pH. Baking soda can be purchased from your local feed store in 50 pound bags. It is used to stabilize the pH of the digestive tract of cattle. To learn more go to Biological-Filter.




Fish Food
tilapia Food should be considered one of the most important decisions concerning the well being of the fish. Many different types of fish food are commercially available. Floating pellets of various sizes and nutritional values are usually preferred for most recirculating systems. However, when fish are very small, they will thrive on brine shrimp, fish flakes, or crumbled commercial fish food which can be added to a gelatin mix to make it easier for the fry to eat. You will want to purchase a food that is suitable for your particular species. Food should be purchased no more than 3 months in advance because it will loose its nutritional value with age. The food should also be stored in a cool dry place. By refrigerating the food the nutritional value will be extended. Do not feed moldy food.




Optimal Feeding Rates
Optimum feeding rates should be approximately 3% of the fish's total body weight per day. Though, fry will greatly exceed that amount. Care should be taken not to feed the fish more than they can consume at one time in order to avoid fouling the system's water. Excess food can also cause imbalances in your biofilter's stability. In order to determine proper feeding rates, random samples of fish weights may be used to calculate the percentage of food to be fed daily. As a rule, fry and small fish should be fed smaller amounts with shorter feeding intervals, and larger fish may be fed larger amounts during fewer daily feedings.



Introducing Fish to Your System
Upon the arrival of your new fish, you should acclimate them to the water in the system. As soon as fish are received, remove them from the box and float the unopened bag in the water for about 30 minutes to allow the equilibrium of the two temperatures. Then the bag should be carefully opened to allow a small amount of water in the bag. About every 10 minutes add about 20% of the water volume to the bag. At this time the fish are quite vulnerable and should be watched carefully. Salt, at the rate of 1/2 pound per 100 gallons of water (2 ppt equals 1.67 Ibs/100 gallons of water, sea water is about 32 ppt) may be used as a stress relief for fish that undergo transportation. We have found no adverse affects to the plants we have grown with this amount of salt in the water.




Marketing Your Fish
Fish are processed in many ways that vary due to either the species or the market for which they are intended. They may be sold to individuals, restaurants, retail fish markets, or fish wholesalers. Your particular state may have regulations concerning processing of fish intended for sale. Questions concerning the legal processing of food fish may be directed toward your aquaculture extension advisor.



Bacteria:

When fish are introduced to the tank, begin seeding your Bio-Filter with bacteria. We recommend you add a tablesthingy of Freshwater Bacteria to the system everyday. It can be put in the Tank, the Bio-Filter, or the Clarifier. Continue adding a tablesthingy a day, as long as ammonia levels are high. When the system is stable and the ammonia is maintaining good levels, there is no longer a need to add bacteria daily. For more information on Bacteria see Bio-Filters and Biological-Filter.




Cleaning The Fecal/Particle Clarifier (1 - 12):

1. Close Gate Valve B, between the Tank (center drain) and the Clarifier.
2. Allow the water in the Clarifier to lower to the top of the ell of Part #4.
3. Close Gate Valve A, between the Tank (airlift) and the Bio-filter.
4. Open Gate Valve C, the drain off to the side of the Clarifier.
5. Allow the Clarifier to drain.
6. Remove the screen, thoroughly spray down, and set aside.
7. Thoroughly spray down the inside of the clarifier, Scrub off build-up as needed.
8. Replace the Screen
9. Close Gate Valve C.
10. Fill the clarifier with de-chlorinated water to
the level it was at previously.
11. Open Gate Valve B.
12. Open Gate Valve A.

It is recommended that the Clarifier be emptied and rinsed every day. To learn more, go to Fecal/Particle Clarifier.







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