Tanks come in every size from small bowls to giant 500 gallon aquariums.
There are many factors you need to consider before buying a Fish
Tank.
If you are not having many fish then you might get away with small
fish tanks. But the Iron rule for anyone is that the bigger it is
the better it is for Fish and you.
It's less maintenance and you can house more numbers of fishes. If you are just starting out you should consider a 20 to 30 gallon aquarium.
You might have seen in movies and other peoples houses. They have
lots of fishes on some sort of Bowl ( specially gold fish). It can
be hazardous for fishes
Fish Tank shapes
Fish tanks come in many shapes as well as sizes. The most common are hexagon and
rectangular, but you can also buy rounded bubble tanks.
Rectangular fish tanks are the best for your water quality and fish health. Since
rectangular tanks are long, the surface area is larger in ratio than fish tanks of other size and allows for better
exchange of gases and, thus a healthier tank.