6.2 Temperature

Water temperature is more important in aquaponics than air temperature. Many water chemistry factors are affected by temperature, such as the amount of toxic ammonia (un-ionized) present and the solubility of oxygen. It also directly impacts the health and survival of both fish and plants. Fish are poikilothermic, or cold-blooded. This means that their body temperature is dependent on water temperature. At extreme temperature, fish will stop eating, becoming lethargic and susceptible to disease. In plants, high temperature can reduce the uptake of essential plant nutrients, such as calcium, force early flowering in cool weather crops, and increase potential for plant roots pathogens like Pythium spp. For this reason, it is important to prevent wide swings in daily temperature. Shading or covering water surfaces, insulating fish tanks and plant beds, and utilizing passive or solar heating in greenhouses are strategies many producers employ. In temperate areas where temperature changes drastically from season to season, producers can alternate fish and plant crops seasonally to reduce heating or cooling costs.

Source: Janelle Hager, Leigh Ann Bright, Josh Dusci, James Tidwell. 2021. Kentucky State University. Aquaponics Production Manual: A Practical Handbook for Growers.