Question

We do not clean ponds or lakes, but aquarium needs to be cleaned. Justify.

Answer 1

We do not clean ponds or lakes , but an aquarium needs to be cleaned because in the Aquarium the uneaten food as well as the waste generated by the fishes mixes with the water and is left untreated due to the lack of decomposers. The waste materials thus accumulate in the water making it toxic. So, it is necessary to clean the aquarium.

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.