Amazon River foodweb
In this relationship both organisms benefit. An example is an Angel Cichlid eating algae. The fish gets its energy and the algae's population will stay under control.
One organism in this relationship benefits and the other is unharmed and unaffected. In a freshwater biome a small fish may hide in a plant from its predators.
In this relationship one organism benefits and the other is harmed. An example is a parasite on a fish. This hurts the fish but helps the parasite.
Pink River Dolphin
This rare dolphin species is a tertiary consumer that eats a variety of fish and snails. It will even eat Piranahs.
This fish is a primary consumer and eats algae and also eats Daphnia.
Daphnia is a crustacean first level consumer that eats algae. This organism is eaten by a variety of small fish.