The adult size of discus fish (Symphysodon) varies depending on their variety, rearing conditions, and genetic differences. 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 centimeters. Some individuals, such as the Heckel discus (Symphysodon discus discus), can grow up to 18 centimeters.
Common artificially-bred varieties (e.g., Red Discus, Blue Discus): Most reach an average body length of around 15 centimeters, while a small number of individuals from high-quality bloodlines can exceed 20 centimeters.
Special Varieties & the Impact of Rearing Conditions
Large-sized varieties: Special strains like the "Tiger Dog Discus" can grow beyond 20 centimeters when kept in ideal environments—such as large aquariums and fed high-protein diets.
Rearing conditions: Several factors significantly influence their growth, including:
Aquarium size: A minimum length of 60 centimeters per adult fish is recommended.
Water quality: Slightly acidic, soft water is preferred.
Nutrition: Diets like beef heart burgers (a common high-nutrient food for discus) support healthy growth.
Growth Stages & Rate
Rapid growth stage: Juvenile fish (growing from 4 to 10 centimeters) typically take about 2 months to reach this size, with a growth rate of up to 1 centimeter per week.
Late-stage growth: Once they exceed 12 centimeters, their growth rate slows down significantly. Some individuals may only gain 1 centimeter in several months, and growth may eventually stop due to genetic limitations.
Lifespan
Wild discus fish generally live for 5 to 6 years.
Artificially-bred varieties typically have a shorter lifespan, ranging from 2 to 3 years.