Saw this posted on another forum and thought it was a pretty interesting read. This is a much debated subject so this (along with a few other studies) may help to give us hobbyist a definitive answer to the question.
http/www.practicalfishkeeping.co.uk/content.php?sid=2927&utm_source=PFK_newsletter&utm_medium=email&utm_campaign=June_16_2010&utm_term=Definitive_guide_to_Discus:_part_two&utm_content=html
"I have examined hundreds of specimens during many years and stomach and gut contents among wild Discus indicate an order of precedence: detritus, then plant material (flowers, fruits, seeds, leaves), algae and micro-algae, aquatic invertebrates and terrestrial and arboreal arthropods.
The Amazon has adapted to nature for fishes during millennia of evolution. Plants of the tropical rainforest have little water and cannot flourish during the dry season so cannot waste energy. The same happens to most freshwater fishes.
During the dry period, with a much reduced water level and hardly any food source — except for predators — many fish starve or feed on the little available, usually detritus.
Discus and many other fishes eat what they can get, but have to be constantly aware of carnivorous predators.
During the six to nine months of floods, almost all trees and bushes, flower and have fruits and seeds — which is the main nutrition of roughly 75% of all Amazonian fishes.
The adults, and babies which grow to adults in that period, can then fill their stomachs and guts.
The carnivorous predators starve as they cannot find their prey in the huge water masses.
How much nutrition?
I have found the following percentage of nutrition in each one of the three species:
* Symphysodon discus during low water: 55% detritus; 15% plant material; 12% algae and micro-algae; 10% aquatic invertebrates; 8% terrestrial and arboreal arthropods. During high water: 28% detritus; 52% plant material; 5% algae and micro-algae; 3% aquatic invertebrates; 12% terrestrial and arboreal arthropods.
* Symphysodon aequifasciatus low water: 52% detritus; 18% plant material; 15% algae and micro-algae; 13% aquatic invertebrates; 2% terrestrial and arboreal arthropods. High water: 8% detritus; 62% plant material; 8% algae and micro-algae; 5% aquatic invertebrates; 17% terrestrial and arboreal arthropods.
* Symphysodon haraldi low water: 39% detritus; 9% plant material; 25% algae and micro-algae; 22% aquatic invertebrates; 5% terrestrial and arboreal arthropods. High water: 6% detritus; 44% Plant material; 12% algae and micro-algae; 16% aquatic invertebrates; 22% terrestrial and arboreal arthropods."
http/www.practicalfishkeeping.co.uk/content.php?sid=2927&utm_source=PFK_newsletter&utm_medium=email&utm_campaign=June_16_2010&utm_term=Definitive_guide_to_Discus:_part_two&utm_content=html
"I have examined hundreds of specimens during many years and stomach and gut contents among wild Discus indicate an order of precedence: detritus, then plant material (flowers, fruits, seeds, leaves), algae and micro-algae, aquatic invertebrates and terrestrial and arboreal arthropods.
The Amazon has adapted to nature for fishes during millennia of evolution. Plants of the tropical rainforest have little water and cannot flourish during the dry season so cannot waste energy. The same happens to most freshwater fishes.
During the dry period, with a much reduced water level and hardly any food source — except for predators — many fish starve or feed on the little available, usually detritus.
Discus and many other fishes eat what they can get, but have to be constantly aware of carnivorous predators.
During the six to nine months of floods, almost all trees and bushes, flower and have fruits and seeds — which is the main nutrition of roughly 75% of all Amazonian fishes.
The adults, and babies which grow to adults in that period, can then fill their stomachs and guts.
The carnivorous predators starve as they cannot find their prey in the huge water masses.
How much nutrition?
I have found the following percentage of nutrition in each one of the three species:
* Symphysodon discus during low water: 55% detritus; 15% plant material; 12% algae and micro-algae; 10% aquatic invertebrates; 8% terrestrial and arboreal arthropods. During high water: 28% detritus; 52% plant material; 5% algae and micro-algae; 3% aquatic invertebrates; 12% terrestrial and arboreal arthropods.
* Symphysodon aequifasciatus low water: 52% detritus; 18% plant material; 15% algae and micro-algae; 13% aquatic invertebrates; 2% terrestrial and arboreal arthropods. High water: 8% detritus; 62% plant material; 8% algae and micro-algae; 5% aquatic invertebrates; 17% terrestrial and arboreal arthropods.
* Symphysodon haraldi low water: 39% detritus; 9% plant material; 25% algae and micro-algae; 22% aquatic invertebrates; 5% terrestrial and arboreal arthropods. High water: 6% detritus; 44% Plant material; 12% algae and micro-algae; 16% aquatic invertebrates; 22% terrestrial and arboreal arthropods."