I have had many fish tanks in the last 15 years. I started off with a small tank and worked my way up to a 500-liter tank. I have to say that I prefer the larger tanks over the smaller ones. Here is why I would suggest going with a larger tank. They cost almost the same to set up in the beginning. You will still need to invest in the tank, the filter, and the air pump. It is a bit cheaper to buy the gravel for a smaller tank than a larger one that is for sure. But the cost of the filter and the air pump cost the same no matter if it is a large tank or a small one. In a larger tank, you won't need to change out the water as often. This is time-consuming and you still need a bowl to add the fish to when changing out the water in the tank. The larger tanks get dirty less often and you don't need to change the water as often in them. In a small tank, you might be able to go for 2 to 4 weeks before changing out the water. No matter what the fish grow and in small tanks, they outgrow the tank much quicker. I found out in a small tank that it is easier to get an infection in the water than it is in a larger tank. You'll end up treating the tank more often for infections.