Wild Royal blue discus
The Amazon basin is home to three main types of water: "loam-yellow" or "white" water in the upper region, "blackwater" near the Rio Negro in the central region, and "green-yellow" or "clear water" in the lower region. Each type of water supports different colored wild discus fish.
Due to the immense rainforests and abundant rainfall in the Amazon, the water in the region is soft, with low levels of dissolved solids (measured in total dissolved solids or TDS). Discus fish breed in a variety of water conditions, but softer water with low TDS levels can improve the fertilization of their eggs and increase fry sizes. Breeders often use reverse osmosis systems or purchase RO-filtered water to replicate the low TDS water in the Amazon.
In the Amazon, discus water typically has a pH between 6.0 to 6.5, but in some places, it can be as low as 4. The temperature ranges from 77 – 84º F (25 – 29 º C). In Southeast Asia, discus are found in soft to medium-hard, alkaline water (3-8 dH, pH 7.0 – 8.0) with temperatures around 81 – 91º F (27 – 33º C).