We have already covered choosing fish for your system, here are other considerations you need to know before you begin.
Fish density:
Stocking rates of 1 pound per gallon can be reached but must be monitored constantly for water quality and oxygen levels. Much less work is a stocking density of 1 pound per 3 to 10 gallons of water, but this depends on how many plants you have to remove the excess nutrients. 25 to 100 square foot of biological surface area is required per pound of fish to safely remove the ammonia and nitrites which are toxic to the fish.
The best fish food for your aquaponics system
Aquaponics is a fantastic way to grow fresh produce and raise fish in a sustainable, symbiotic system. However, choosing the right fish food is crucial for the health of your fish and the overall success of your system. Here’s a guide to the best fish food options for aquaponics, considering whether your fish are herbivores or omnivores.
Herbivore Fish Species
Herbivorous fish primarily consume plant material such as algae, aquatic plants, and phytoplankton. Some popular herbivore species include tilapia and catfish. For these fish, the best food options include:
Aquatic Plants: Duckweed, water lettuce, and azolla are excellent choices. These plants are nutrientrich and can be grown within the aquaponics system itself.
Vegetables: Leftover vegetables from your kitchen such as spinach, lettuce, and zucchini, can be fed to herbivorous fish.
Commercial Pellets: Look for specially formulated herbivore pellets that contain high-quality plant-based ingredients.
Omnivore Fish Species
Omnivorous fish have a more varied diet, consuming both plant and animal matter. Common omnivore species in aquaponics include tilapia, some species of bass, and catfish. For these fish, consider the following food options:
Commercial Pellets: Omnivore-specific pellets that contain a balanced mix of plant and animal-based ingredients.
Insects and Worms: Earthworms, mealworms, and black soldier fly larvae are excellent protein sources for omnivorous fish.
Vegetables and Fruits: Similar to herbivores, omnivores can also benefit from leftover vegetables and fruits.
Small Aquatic Animals: Brine shrimp and other small aquatic creatures can be added to the diet for additional protein.
Feeding the fish:
A healthy fish will consume between 2% and 5% of their total body weight a day. Over feeding your fish is the best way to upset the system as well as underfeeding the fish will influence the nutrient levels that the plants need to consume to thrive.
Oxygen requirements:
Between 3mg and 8mg per liter is normal for the fish to survive. Every type of fish has different levels of O2 that they can live in, but that is a safe range for most fish types. The oxygen levels can be raised to 15 parts per million which will accelerate growth in both the fish and plants.
This sums up the considerations when choosing fish. Next month, we will dive into choosing which plants we want growing in our aquaponics system.
Till next time!
Joe Leveridge
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