Not taking the time to select an appropriate size for a fish tank is a mistake many people make when starting their aquarium, this can cause many problems.
Firstly, decide what kind of fish you would like to keep, its much better to pick the type of fishtank you’d like based on the species of fish rather than the other way around.
Another important point – take measurements before buying your fish tank! This sounds very basic but too many people end up with fish tanks that are too big to fit into the space they were planning to put it.
As a general pointer – bigger is better.
A common misconception is that smaller fish tanks require less maintenance than bigger tanks. This is a complete misconception. Smaller fish tanks are harder to maintain Due to the smaller amount of water that you have to work with. Large fish tanks hold much more water, therefore any problems you have are dispersed over a greater volume of water.
A bigger fish tank is less susceptible to rapid changes in temperature and other water conditions which may stress the fish. A larger fish tank will also provide more space for you to make modifications to your aquarium such as the addition of ornaments or other water plants you may desire in the future. A larger fish tank contains more water, making it easier to dilute any chemicals and other pollutants which may cause harm to the fish. Finally, a larger fish tank just looks more impressive.
Make sure your fishtank is placed away from external sources of heat/light/pollution.
This includes near windows, air conditions, heaters, stoves, kitchen areas, dining areas, air vents etc.
Even if your fishtank is far away from a window, make sure it doesn’t receive too much direct sunlight because this will lead to rapid algae growth and excessive heat which will very quickly pollute your fishtank.
Another problem with a fishtank that is too small is the buildup of harmful substances. Through respiration, fish constantly produce ammonia. If the water level is too low then the ammonia level will increase faster than the aquarium can filter it. Many fish will also die in small fish bowls because the tank is too small and weak to install a suitable filtration system.
Although fish live in water, they need oxygen to survive just like any other living organism. If the tank is too small, the surface area of the water will limit oxygen gas exchange from happening between the atmosphere and water. Fish will die from a lack of oxygen.
A small tank is also very hard to clean. A misconception is that a smaller tank will have a smaller area to clean and change water. A larger fishtank is far easier to maintain because you can install filtration systems which will greatly reduce the required frequency of cleaning. It is better to wash 5 plates once a week than 1 plate 5 times a week.
A small tank restricts space for fish to swim around, lowering swimming room. A lack of swimming room can stress out fish, stressed fish have a weakened immune system and become more susceptible to death and disease.
A restricted space also prevents the growth of aquatic plants and other organisms which help contribute to a functional aquatic ecosystem. This will reduce the organic balance of your fishtank, causing a wide range of undesirable problems.
In conclusion, always go for the largest tank possible!
General rules of fish tank size:
The fish tank must be at least 5 gallons (20 litres).
This is the size of 2 medium sized buckets.
Even for keeping a single betta fish, the minimum recommended bucket size is 2 gallons. Anything smaller than this and the water conditions will be very difficult to keep stable, making it a headache to keep fish.
What about the smaller fishbowls that are common in petstores? You can still keep fish in smaller fishbowls but their health will not be nearly as good as a larger tank. Due to the many problems mentioned above, (fluctuating temperature, pollutants, lack of space to install filter, disease, stress), fish in smaller tanks are not nearly as healthy as those happily living in larger tanks.
Fish tank sizing myths:
Inch per gallon rule (not true!)
This rule states that you should not get more than an inch of fish for every gallon of water you have. This rule is not true.
Length itself is a not an adequate method to measure the size/requirements of fish. Fish come in a variety of different body sizes and weights. A goldfish can weigh up to 10 times a tropical fish of the same length. With a greater body mass, they will produce more waste and require a larger tank.
Despite their popularity and cheap price, goldfish are an extremely messy species of fish to keep. The grow extremely quickly and produce a lot of waste. For a single fishtank, as much as 20 gallons of water is recommended, with no less 30 gallons for two. It is essential that you have enough water and an adequate filter installed in your aquarium to prevent problems, otherwise you’ll have to change the water every day.
The fish WILL outgrow the tank.
Another misconception is that the fish will not outgrow the tank, there is an incorrect belief that the size of the tank doesn’t really matter because the fish will simply stop growing in size and remain at a stable state when it detects that the size is no longer large enough to accommodate it. This assumption is entirely wrong, there is absolutely no reason for a fish to stop growing naturally if a tank isn’t big enough. It may stop growing, but that’s due to disease/stress, not natural survival mechanisms. When a fishtank becomes too small for a particular fish species, the fish will simply outgrow the tank size causing maintenance to be an absolute chore.