A fresh water biome food chain is likely to be made up of micro-organisms, decaying substances, detritus, animals without backbones, small fish, large fish, eels and birds. The animals may be present in different species depending on the physical location of the particular biome.
A food chain normally represents the relationship of organisms within a given ecosystem. The food chain shows how each organism is important to the other and the ecosystem as a whole.
At the bottom of the food chain in a fresh water biome one is likely to notice micro-organisms and decaying substances. These are the basic things that enable life to begin. Right on top of these things are likely to be plants such as phytoplankton. On the next level are animals without backbones such as stonefly, midge, caddis and mayfly. These animals are at this position because they are able to eat the plants available.
The next level of the food chain is likely to have small fish which feed on the animals without backbones. Right on top of small fish are large fish which are able to eat both the small fish and some animals without backbones.
On top of the fresh water biome food chain, one is likely to notice birds such as ducks and herons which feed on all kinds of fish.