We do not clean ponds or lakes, but an aquarium needs to be cleaned regularly. Explain. fast...
Answers
We do not need ponds because there are smaller creatures living in them like plankton, bacteria & other microbes which usually decompose dead organisms and consume them. So the presence of these organism makes a self cleaning mechanism in ponds. so we don't need to clean ponds.
These things are absent in aquarium so we have to manually clean the aquarium regularly.
When it comes to an aquarium, the management of that aquarium should have to maintain perfect environment and pH of the waters. For maintaining the perfect environment they have to clean the nitrate content of the waters in a regular interval. They have to choose certain plants, rocks and oxygen level for certain fish species. If any one thing goes wrong, then it will be too hard for certain fish species to survive the enclosed environment.
Apart from the aquariums, natural aquatic environment have own kind of maintaining facilities, we can call them microorganism. The interdependence between the species in a particular environment makes the environment self sustain.