7.8 CHAPTER SUMMARY

Standard manufactured fish feed pellets are recommended for use in aquaponics because they are a whole feed containing the correct balance of proteins, carbohydrates, fats, vitamins and minerals needed for fish.

• Protein is the most important component for building fish body mass. Omnivorous fish such as tilapia and common carp need about 32 percent protein in their diet, carnivorous fish need more.
• Never overfeed the fish, and remove uneaten food after 30 minutes to reduce risks of ammonia or hydrogen sulphide toxicity.
• Water quality needs to be maintained for fish. Ammonia and nitrite must be close to 0 mg/litre as they are toxic at any detectable levels. Nitrate should be less than 400 mg/litre. DO should be 4-8 mg/litre.
Tilapia, carp, and catfish are highly suitable for aquaponics in tropical or arid conditions as they grow quickly and can survive in poor quality water and at lower DO levels. Trout grow well in cold water, but require better water quality. Fish health should be monitored daily, and stress should be minimized. Poor and/or changing water quality, overcrowding, and physical disturbance can cause stress, which may lead to disease outbreaks.

Abnormalities or changes in physical behaviour can indicate stress, bad water quality, parasites or disease. Take the time to observe and monitor the fish in order to recognize symptoms early and provide treatment.