It is made up by combination of kalash, leaves of mango tree, water, coconut, sign of swastika and flower. Each combination represent something like kalash represent the unity, leaves of mango tree represent the creation, swastika represent the wealth, water represents the life, coconut represents the human skull and flowers represent the happiness. The mangal kalash is the combination of all and is placed at any good occasion in the house.
According to Vastu Shastra the aquarium of twins fishes should be placed in a dining room of the house which makes you wealthy and remove all the vastudosh of your house. It is very good to see it early in the morning and increases the happiness in the family. The first incarnation of lord Vishnu on earth is in the form of fish and the nature of fish is active and moveable so by putting it in the house represent that the lord of house always gain progress in his life. It also make the strong relationship between the couple of that house.
Sculpture Of Lord Ganesh:
As you know the lord Ganesh is also known as the god of wit. It remove all the negative energy of the house and bring a wealth and happiness, It remove all the obstacle of the life and bring the peace in a family.