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Tips for the Beginning AquaCulturist
By Myles Harston 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.
In all recirculating aquaculture systems there are five basic components:
1. The culture tank where the aquatic animals are kept.
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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