I had been said before that fishes are just as much as dependent upon oxygen as we are. So we could not put many fishes into one of these tal narrow water tanks which are designed to stand on window sills. One way to calculate the number of fishes you can put in a water tanks is to find out the size of the surface area. We could measure the length and multiplying it by the width of the water tank. For example : water tanks with twenty inches long and and ten inches wide equal to two hundreds square of surface area. Each fishes has its own needs of surface area just like illustration I had mentioned before in "
Aquarium".