Piranha Ecosystem, Biotopes and Aquariology

Defining a term for piranha hobbyists

by Frank Magallanes








Grouping species like these S. sanchezi can be fatal or near fatal to other tank mates. The species is a notorious scale and fin biter. It will also keep nibbling away at the poor hapless fish that loses all its fins, until only a partial body remains! However, keeping them together as a singular group species can be a chore. Some success has been reported in large public aquariums, as well as mixing with Pygocentrus.


Most hobbyists dream of having an Amazonian ecosystem in their home. Problem is, you can't have a river system or pool of water that would harbor the countless animals found in that system. Instead what you the hobbyist can do is create a mini-ecosystem that can be a model of the larger scale found in Amazonia. Ecosystem has a broad use in the aquarium hobby as well as in scientific literature. Ecosystems show relationships with groups of organism and to each other and their environment. Accordingly, the following describes what an ecosystem consists of:


Ecosystems are composed of a variety of living organisms that can be classified as producers, consumers, or decomposers. Producers or autotrophs, are organisms that can manufacture the organic compounds they use as sources of energy and nutrients. Most producers are green plants that can manufacture their food through the process of photosynthesis. Consumers or heterotrophs get their energy and nutrients by feeding directly or indirectly on producers. We can distinguish two main types of consumers. Herbivores are consumers that eat plants for their energy and nutrients. Organisms that feed on herbivores are called carnivores. Carnivores can also consume other carnivores. Plants and animals supply organic matter to the soil system through shed tissues and death. Consumer organisms that feed on this organic matter, or detritus, are known as detritivores or decomposers. The organic matter that is consumed by the detritivores is eventually converted back into inorganic nutrients in the soil. These nutrients can then be used by plants for the production of organic compounds.


In using piranhas genera Pygocentrus, Serrasalmus, Pristobrycon and Pygopristis, we identify heterotrophs or commonly called carnivores. Silver Dollars (herbivore) genus Metynnis are also heterotrophs, but they eat autotrophs commonly known as plants. We can now define what makes up a piranha ecosystem. For this you will need an aquarium, water, gravel, plants, feeder fish and a filtration system to create anaerobic bacteria. Living together, this term does not require compatibility nor is it limited to just piranhas. It can be a closed system (not recommended for piranhas) or open system where you provide the food and other nutrients.


Aquarists could adopt this term piranha ecosystem as most accurate when they are mixing species or attempting to add non-piranha fish to their aquarium. A practice I do not recommend for the home aquarium. Few hobbyists, for example, have the knowledge to accomplish such a setup as described above. It certainly would have its problems though on a small scale such as a piranha aquarium.


Some examples of species mixing


On line information useful information for aquarists:

  1. Follow this link http://www.fi.edu/tfi/units/life/habitat/habact1.html and will provide you good advice on how to keep records.

  2. Students can also find out why cohabitate is not a proper word to use with piranhas.

  3. Find out why shoal may not be a good word to use with piranhas. Included in this work is why you shouldn't  mix species of piranhas.



So what can we call a piranha aquarium? Basically, you can call it just that, a piranha aquarium or if you want something much more accurate the word "biotope." David M. Schleser, a biologist, professional photographer, author, and personal friend I deeply respect, used this term in his book on piranhas in the aquarium. The definition of a biotope is a small habitat in a large community. 




Another term is aquariology (Gratzek et al, 1992), which  is the study of keeping fish in aquaria. It explores the reasons for keeping fish and requires a knowledge of the biological characteristics of fish, as well as of such aspects of their husbandry as feeding and nutrition. It also pertains to reproduction, water quality management, sources and control of stress, with disease control. This term is my favorite since I have used a variation of it for a number of years; Piranha Aquario.







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