There are many people who keep bettas in very small containers, too small to be considered legitimate aquariums. Some are so small that you can’t even fit a full cup of water in them. However, many of these owners claim that this is how bettas are supposed to be kept, and even going as far as to say that it is the safest type of container to keep bettas in. If this is true, at what size would a tank start to be harmful?
This is not at all true, and it is uncertain as to where this misinformation came from. Betta fish do not struggle to swim in large tanks, as some may suggest, and actually tend to be more active in larger tanks. Whether you put your betta in a 5-gallon or 55-gallon tank, they will not have a hard time thriving if you are taking proper care of them. A betta will use all the space provided to them, and it is always better to go bigger if you can.
In this article, we will discuss whether or not a tank can be too large for a betta, the water chemistry differences of small and large tanks, whether or not a 10 gallon is too big, maintenance for larger tanks, and the smallest aquarium size you can keep a betta fish in.
Can a Tank Be Too Big for a Betta?
In terms of a betta struggling with the amount of water, a tank cannot be too large for a betta. However, it is easy to accidentally buy a tank that is larger than you can maintain, or one that is too heavy when full, or too expensive to heat 24/7.
When you buy a tank, you need to ensure that you have the proper amount of space for it and that your floor will support it. A simple 30-gallon tank normally weighs about 300 pounds when full of water, gravel, and decorations. While most homes won’t have an issue supporting the weight of a person and a half, some apartments and older homes could have issues supporting that weight long term. More often than not, a 300-pound aquarium isn’t something that gets moved around too often.
In addition, betta fish require heated aquariums in order to thrive. They need their water heated to a constant and consistent 78-80 degrees, which, if you have a larger tank (larger than 30-gallons), it may be more expensive than you initially thought.
The water bill will increase, as large tanks still need weekly water changes. However, the increased cost of water and heat generally won’t break anyone’s bank, but they are factors to consider. As long as you are able to maintain and upkeep a large tank, you could put your betta in a 100+ gallon tank without your little fish experiencing any problems.
Water Chemistry of Large Tanks vs Small Tanks
As previously mentioned, there is a significant difference in the upkeep of a small tank versus the upkeep of a larger tank. The primary bonus to having a large tank is stability; it takes a lot more to upset the chemical balance, temperature, and salinity in a large tank than a small tank. Small tanks, starting at sizes considered the minimum requirement for bettas, are prone to massive temperature fluctuations.
A good rule of thumb is to prevent the temperature from fluctuating more than 2 degrees Fahrenheit per hour. Of course, there are some instances in which this is not possible, but it is a general recommendation. If the temperature fluctuates more than this, you can risk sending your fish into shock.
In addition, just one decaying food pellet that your betta missed could ruin the chemistry of a small tank. It could cause ammonia and subsequent nitrite spikes, as well as increased nitrates. In a large tank, the amount of ammonia released by a single piece of decaying food will be too small to affect the overall tank chemistry.
A larger tank is better for beginners because beginners are much more likely to accidentally overfeed, forget to do weekly water changes, or make several other mistakes. Large tanks are much more forgiving, while a mistake in a small tank is often lethal.
Large tanks are similar to playing the aquarium hobby on “easy mode”, as there is some wiggle room for mistakes. While a beginner can start with a small betta tank, they will have to be extremely vigilant in testing the water, as well as doing larger water changes per week (in terms of the percentage of the tank water that needs to be changed), which can cause irregularities in the water hardness, or even cause nitrate shock.
Is a 10-gallon Too Big? Is it Too Small?
A ten-gallon is a great size to have when you are first getting betta fish. A betta will be able to entirely use the space provided, though there are not many options for tankmates in a 10-gallon tank. A tank of this size is many times more stable than a 2.5 gallon, has more filter options available, and is easier to clean than a smaller tank.
For many of the small “betta tanks” ranging from 2.5 to 3 gallons, there are only a small handful of filter and heater types and sizes available. Many of the tanks are unique sizes or shapes, especially the round ones. The round ones are incredibly difficult to fit with a filter and basically always require an internal filter, which greatly reduces the water volume.
A ten gallon can be fitted with many different types of heaters, even some rated a bit above 10 gallons, as long as you have good circulation. You will also be able to choose between internal, sponge, corner, Hang on Back, and even small canister filters.
While the water chemistry will not be as stable as it would be in larger tanks, if your only occupant is a betta, even a beginner won’t have trouble keeping the ammonia and nitrite at zero. Betta fish tend to only be inactive in small tanks, so expect your betta to be using all of their newly available space. Even if your betta has long fins that drag them down, you will notice a significant difference in activity, and they will still love and appreciate their new space.
Is Maintenance More Difficult for a Large Tank?
Maintenance is not necessarily more difficult for a larger tank, though you may want to use different equipment. If you were using a gravel vacuum and buckets for a 2.5-10 gallon, this is perfectly fine and easy to do. However, if you want to do your weekly 25% water changes on a 30+ gallon with buckets, it will soon become a dreaded task.
Luckily, there are several inventions that can help you with your weekly aquarium maintenance. Python is my personal favorite. One end connects to your sink and the other has a gravel vacuum attachment. All you need to do is connect it, make sure it is set to draw water out of the tank, and turn on your faucet. This creates suction and you can vacuum your substrate as normal, with all of the filth going straight down the drain.
Next, you need to match the sink’s temperature to the temperature of the tank. Close the end of the part that connects to the sink, turn on your sink, and let the freshwater flow right into the tank. At this point, you should dose enough water conditioner for the volume of your tank.
Small tanks generally need water changes more frequently than once a week, as well as requiring spot cleaning nearly every day. While it is not a bad habit to spot clean frequently, large tanks do not need it daily, and once a week is fine. Weekly water changes should be done on any tank regardless of size, but larger tanks do not need water changes more than once a week.
What is the Smallest Tank I Can Keep a Betta in?
The smallest tank you can keep a betta fish in is 2.5 gallons, though this only applies to males with excessively long fins. The long fins will inhibit their swimming and activity, so it is possible to keep them in smaller tanks. For males with average or small fins or any female, the minimum tank size is 5 gallons.
These bettas are much more active, and while they would benefit from a larger tank, a 5 gallon will do. 5 gallons have some options for non-internal filters, though not many. A small Hang on Back or H.O.B. filter will normally be the best choice for this type of tank.
In a 2.5 gallon, you will only be able to have a single betta (as opposed to 5 and 10 gallons, where you have the possibility to add some invertebrate tank mates) and that one betta will require a lot of care. Waste builds up very quickly in such a small tank. You may need to do water changes every 2-4 days just to keep the nitrates down.
In addition, you will need an effective filter to circulate the water, and the tank cannot be placed anywhere that the temperature easily changes (e.g. by a window, near a vent, near a furnace or fireplace, etc.). In such a small volume of water, the temperature can fluctuate severely. Simply placing it in a vulnerable area could be enough to cause lethal temperature shock.
In conclusion, there is no tank too large for a betta fish, as long as it isn’t too large for you to manage. Betta fish, contrary to popular belief, are generally very active and curious fish and love to explore. Providing them a large tank cannot be harmful, as long as the filtration, heating, and other necessities are properly done. The minimum tank size for an impaired betta is 2.5 gallons, though these are difficult to manage, and the minimum size for a normal betta is 5 gallons.