Do you have a pond or a lake? It’s actually not as easily or definitively answered as you might think. Although it is generally understood that a pond is smaller than a lake there is no specific calculation to tell you which you have in your yard.
A definition for a pond could be ‘bodies of water where light penetrates to the bottom of the waterbody’. It could also be ‘bodies of water shallow enough for rooted water plants to grow throughout’. Another could be ‘bodies of water which lack wave action on the shoreline.’ However not everyone agree with this.
I think whatever you have in your yard, pond or lake, it will have similar characteristics. You will want to ensure that it remains healthy and vibrant. That will necessitate sufficient aeration and a good balance of nutrients so you may want to invest in an air pump and pond additives.