Ideal fish for the ECO-Cycle Aquaponics system are smaller tropical fish and goldfish. One inch of fish per gallon is a common aquarium stocking recommendation. This is a very loose target, however, and the actual number of fish will vary depending on the types of fish and their species-specific care requirements. For fish like guppies, platys, swordtails, small tetras, danios, rasboras, and other peaceful community fish, one inch per gallon is a good target. Goldfish produce a lot more waste and therefore fewer are needed to stock the tank.
As with any aquarium, biological filtration is required to keep the system balanced and safe for the fish. Nitrifying bacteria process the fish waste (ammonia), eventually converting it into nitrate (NO3) — which in aquaponics is utilized by the plants. Bio-filtration is accomplished by moving oxygenated water through a substrate or media with high surface area, on which nitrifying bacteria colonize. The blue filter brick in your ECO-Cycle provides this surface area. “Cycling” is the process of building up nitrifying bacteria colonies in the bio-filter. The initial cycle of building up sufficient nitrifying bacteria takes about 4-6 weeks.
It is important to introduce the fish incrementally, starting with just two or three. Once the system has “cycled”, the tank will be ready to handle a larger bio-load. From there, fish may be added incrementally in small numbers until the target number is reached.
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