The water temperature in aquariums is of crucial importance for animals and plants and must be monitored. Most tropical ornamental fish feel most comfortable at temperatures between 24 and 26 °C. However, there are also fish that prefer lower temperatures. The discus is one of the fish that find higher temperatures between 27 and 29 °C to be ideal. Axolotls and many freshwater shrimps prefer cooler temperatures.
The water temperature can be raised with the help of heater thermostats (JBL PROTEMP s or JBL PROTEMP e) and lowered with the help of coolers (JBL Cooler).