Why is fish tank considered a mini-ecosystem

[Bayo]

Hello there,

Could you explain/elaborate on why is a fish tank considered a mini-ecosystem?

I'm pretty sure this can be considered a silly question, but I would like to know what do you think of this.

Cheers

 

[maxwellag]

It's because it has a system of recycling nutrients. The fish make waste and the plants use the waste, much like a pond. There is also the nitrogen cycle, which is in every aquatic ecosystem-tank or pond, stream or ocean.

 

[mfdrookie516]

Because it's small in comparison to the real thing?