Grow Out Management
4.5 Plants
Stocking and harvesting strategies can also be implemented in the hydroponic portion of the system. The three most common strategies are staggered cropping, batch cropping, and intercropping (Rackocy et al. 2006). Their implementation and success depend on geographic location (tropical or temperate regions), crop variety (leafy vs. fruiting crops), and market demand. Aquaponic producers typically grow leafy green crops, which have a lower value per unit value and high yield. Lettuce, Swiss chard, kale, basil, and other herbs are typically ready for harvest between 3-5 weeks from transplanting (6-8 weeks from seed), resulting in a steady income stream.
· Kentucky State University4.4 Fish Stocking
Fish culture should be well planned, as mismanagement of densities within the system can lead to issues with nutrient build-up/deficiencies, solids accumulation, water quality concerns, and poor fish health. Consider that aquaponic systems typically do not operate with a fish density exceeding 0.5 pounds/gallon. Three of the most common fish production plans are sequential rearing, stock splitting, and multiple rearing units. Sequential Rearing: Sequential rearing involves one tank, containing multiple age-groups of fish (Rackocy et al.
· Kentucky State University4.3 Fingerling Production and Supply
Fingerlings for fish culture can either be obtained from a supplier or produced in-house. Availability, price, number of fingerlings needed, and level of expertise are the main factors that determine the method of choice. Type of species cultured, season, and location can also heavily influence the methods. Supply: The best option for small-scale producers is to buy from a supplier. Suppliers should maintain detailed breeding records, use high-quality broodstock, and implement Best Aquaculture Practices (BAPs).
· Kentucky State University4.2 Species Overviews
Tilapia: Tilapia (usually Oreochromis niloticus or the Nile tilapia) are the most cultured fish in aquaponic systems. They are tolerant of both crowding and relatively poor water quality conditions. They do best at water temperatures of 25-30°C. At temperatures < 24°C, their growth slows substantially, and they become susceptible to disease. They breed readily and abundantly. In fact, if using mixed sex fish, unintended spawning in the system can be a problem particularly in DWC beds where tilapia will consume all available plant roots.
· Kentucky State University4.1 Suitable Species of Fish for Culture
Unfortunately, not all fish species adapt well to tank culture, just as not all animal species adapt to being farm animals. Since fish are cold blooded, almost everything about their growth and health is influenced by temperature (see Tables 4 and 6 for details). The temperature of the culture water will partially dictate what species can or should be raised in your system. Other important factors will be how densely you intend to raise them and for what purpose or market.
· Kentucky State University