Choosing Fish for Your Aquaponic System
When choosing fish for an aquaponic system it helps to look at the environment the system will operate in as well as what infrastructure (greenhouse, house, garage) will compensate for temperature fluctuations. Check out Tricia’s video on Aquaponics where she tours an aquaponic system producing food in the middle of a cold winter!
First and foremost the environment is going to dictate, to a large degree, the kinds of fish you are able to raise. Infrastructure, such as a greenhouse, will allow you to stretch your natural environment to some extent. Figure out what kind of water temperatures your aquaponics system will provide and match it to the types of fish that enjoy that environment. No sense in trying to grow trout in Arizona unless you are capable of providing for their needs.
Some key things to look for when selecting fish for an aquaponic system:
1. Capable of surviving within your temperature range for your location.
2. What is legal to keep in your area.
3. What is available to you.
With these three things in mind here is a list of common fish used in aquaponic systems and their specific qualities:
- Commonly used in aquaponics
- Warm water fish (74-78°F)
- Tolerates pH shifts, temperature changes, high levels of ammonia and low dissolved oxygen levels.
- Omnivorous - eats pellet fish food, duckweed and veggies
- Grows to harvest size in about 6-9 months in ideal conditions.
2. Yellow Perch
- Good for re-circulating systems (aquaculture)
- Cool water fish (68-74°F)
- Tolerates lower dissolved oxygen levels and adjusts to pH changes.
- Eats pellet fish food and veggies.
- Grows to harvest size in about 9 months.
- More challenging to raise
- Cold water fish (64-68°F)
- Can be carnivorous and will eat smaller fish.
- Sensitive to pH changes and water quality
- Requires high levels of dissolved oxygen.
- Eats pellet fish food.
- Grows to harvest size in 12-16 months.
4. Bass, Bluegill, Catfish
- Often raised in ponds and in re-circulating systems
- Warm water fish (80°F)
- More sensitive to temperature, pH changes and water quality.
- Eats pellet fish food, bottom feeders
- Grows to harvest size in: Bass 15-18 months, Bluegill 12-16 months, Catfish 5-10 months
5. Koi, Goldfish, Carp
- Great for an aquaponic system in which you plan to not eat the fish
- Cool water fish (65-75°F)
- Omnivorous - eats pellet food or flake and bugs
- Feed fish 2 - 3 times a day but don’t overfeed. This can be achieved by only feeding fish what they can eat in 5-10 minutes. Utilize a high quality organic pelleted fish food to ensure that the fish are receiving a well rounded diet, this will help prevent the fish from becoming sick or stressed. A healthy fish is the first line of defense to maintaining an aquaponic system.
- It’s best to observe fish during feeding and notice their nature. They won’t eat if they are too cold, too hot or stressed. Monitor the the water quality and temperature (Floating Water Thermometer - Aquaponics TM915) to ensure that the fish are in the optimal conditions. Test water quality every other day for the first month, then about once a week or as needed.
- A water heater (Water Heater 400 Watt - Aquaponics GP1340) will ensure that the fish are kept at the optimal growing temperature which will greatly influence the health and well being of the fish as well as influence their growth rate.
Fish Stocking Density:
- .25 pounds of fish per gallon (conservative) to .5 pounds of fish per gallon (moderate)
- Essential to know what the harvest size of the fish will be to determine initial stocking density
- What size tank will be utilized
Take for instance that fish harvest size will be 1.0 pounds and we have a 100 gallon tank.
Tank size = 100 gallons
Harvest size = 1.0 pounds
First we take our 100 gallon tank and multiply by our conservative stocking density of .25 pounds for a total of 25 pounds.
Total number of fish is then 25 pounds divide this by our harvest size which is 1.0 pounds for a total of 25 fish.
Startup fish at 20% of total capacity (25 fish x 20%) = 5 fish.
So for a 100 gallon tank 5 fish would be what to start with.
Although the math may seem concrete this does not always transfer over to a living system. Always monitor the fish and get to know their habits. Selecting fish for an aquaponic system should be based on the habitat that you can provide for them, the fish that are available to you and as always don’t forget to be sure to check local regulations regarding species of fish allowed.
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