The size of discus fish varies depending on their variety, rearing conditions, and genetics. Below is a comprehensive overview of key information:
Wild vs. Common Cultivated Varieties
Wild discus fish: Their body length typically ranges from 14 to 16 cm. Some individuals, such as the Heckel discus (Symphysodon discus discus), can grow up to 18 cm.
Common artificially-bred varieties (e.g., Red Discus, Blue Discus): Most reach an average body length of around 15 cm, while a small number of individuals from high-quality bloodlines can exceed 20 cm.
Special Varieties & the Impact of Rearing Conditions
Large-sized varieties: Special strains like the "Tiger Dog" discus can grow beyond 20 cm when kept in ideal environments—such as large tanks and fed high-protein diets.
Rearing conditions: Several factors significantly affect their growth:
Tank size: A minimum 60 cm-long tank is recommended for a single adult discus.
Water quality: Slightly acidic, soft water is required.
Nutrition: Diets like "beef heart burger" (a common high-nutrient feed for discus) support healthy growth.
Growth Stages & Rate
Rapid growth phase: Juvenile discus (growing from 4 to 10 cm) take about 2 months to reach this size, with a growth rate of up to 1 cm per week.
Late-stage growth: Once they exceed 12 cm, their growth rate slows down. Some individuals may only gain 1 cm over several months, and growth may stop entirely due to genetic limitations.
Lifespan
Wild discus fish live for 5 to 6 years.
Artificially-bred discus fish typically have a lifespan of 2 to 3 years.