What Happens If You Have Too Many Fish in a Tank?

Too Many Fish in a Tank

If you love fish and own an aquarium, you are certainly not alone. Watching fish in a tank can actually lower your blood pressure, and the more fish you have in there, the more you can enjoy them, right? Not necessarily. While having lots of fish in your aquarium can be fun, there is such a thing as having too many fish in there, and there are legitimate reasons why this is so. It isn’t because fish don’t like a lot of company; it has to do with the oxygen and other components that are in the water and what they can do to the fish in some circumstances.

Reasons Not to Put Too Many Fish Into Your Tank

There are numerous reasons not to overcrowd your aquarium with fish, and it starts with the fact that the tank runs out of oxygen if there are too many fish trying to compete for it. Fish breathe dissolved oxygen by filtering the water with their gills. While it’s true that you can increase the amount of dissolved oxygen by adding an air stone and an air pump, it is still going to be limited in its capability. The bottom line is, it’s impossible for the oxygen to sustain that many fish in an aquarium, so it’s best not to even try.

Besides this, the filter you’re using to make sure the ammonia level doesn’t get too high might not be able to accommodate all of the fish you have in the tank. Fish produce ammonia, but if the ammonia level gets too high, it can still kill them. Filters are there to convert the ammonia into nitrate, but with too many fish in the tank, they cannot convert it fast enough to make a difference. Add this to the list of reasons why you don’t want to put too many fish in your fish tank.

Should You Count the Number of Fish in Your Tank?

It’s likely you’ve never said to yourself, I have too many fish in my tank. You may not even know you have too many, but how many is too many? That depends on the tank itself and the type of fish you have. Some experts recommend no more than one inch of fish for every gallon of water in the tank, but this rule leaves a lot of room for error. For instance, one 10-inch fish will be more cumbersome than 10, one-inch fish, and a full-bodied 5-inch fish will naturally create more waste and take up more “resources” than a 7-inch fish that is slim.

This is why the “one inch for every gallon” rule should only be used as a rough estimate. It is also why looking at the surface area of the water is usually a better way to determine how many fish to place in your tank. A better rule of thumb is to include one inch of fish for every 12 square inches of surface area. One of the many reasons why this calculation is usually preferred is that it takes into account aquariums that have different shapes. In addition to both of these rules, other things need to be considered as well. They include the following:

  • The more fish you have, the better filtration system you should have.
  • If you have a lot of fish, cleaning your tank the old-fashioned way is best. Add small amounts of fresh water and make sure you vacuum up the fish waste.
  • When you transfer fish from dirty water into fresh water, don’t do it quickly because it will be a shock to their system and could kill them.

This will help control the population of the fish you do have so that there aren’t too many in your tank, and if you need a few more reasons why limiting the number of fish in your fish tank is so important, keep reading.

Some Additional Important Tips

So when you ask yourself, how many fish in a tank is a good number, just know that the exact number may not be as important as the size of the fish and what type it is. A lot of things go into making sure you don’t have too many fish for the size of your aquarium, so you’ll need to take numerous things into consideration before you decide if you have too many fish or just the right amount. If you have different types of fish in the same tank, it could be a little more challenging, but if you do your research and ask for assistance from the store where you got the fish, you should get a good answer for your particular situation.

In addition, keep in mind the following, which could happen if your fish tank has too many fish in it:

  • Having too many fish is costly to maintain.
  • If the tank has too many fish in it, there is a greater chance that the fish will get overly aggressive and that some may even be killed in the process.
  • If there are too many fish in a tank, they will not have enough room to swim, which is important to their behavior and their ability to thrive.
  • If there is too much nitrate in the tank, the fishes’ immune systems could be compromised. This means your tank may need water changes more often than once a week.
  • If you have too many nutrients in the tank, it could cause algae to form. Keeping fewer fish in the tank uses up those nutrients and keeps them at the right level.

Having said all this, it’s also important to note that if there are too many fish in your aquarium, it just isn’t as much fun to watch them as they swim around in the water. Not that this will affect their ability to thrive in any way, but it’s still something important to keep in mind. Putting an appropriate number of fish into your fish tank is always important to their well-being, and it is just less expensive, simpler, and less worrisome to do so in the long run.

Are There Other Rules You Should Follow?

The main thing to remember when filling your aquarium up with fish is that there are no “hard and fast” rules when it comes to the number of fish that should be there. In your fish tank, your fish will breathe, eat, and of course, poop, so you have to keep those things in mind when deciding on a number. You’ll also want to keep your ammonia and nitrite numbers down – as close to 0 as possible, in other words. If these numbers get too high, it means you have too many fish in there.

You should also keep in mind that fish do get bigger. Some of them can get up to 12-inches long, as a matter of fact. The bigger your fish get, the more crowded your aquarium will be, and that’s not what you want. All of these “rules” for determining how many fish is “too many” are just basic rules, which essentially means it is a starting point.

The final decision that you make will depend on all of the factors mentioned so far, and it’s best to keep all of them in mind when deciding how many fish to place inside of your aquarium.

***FishKeeperGuide is supported by readers. If you click one of my links, I may earn commissions. I am also participant in the Amazon affiliate program and I will also make a commission from qualifying purchases.
Thank you***

Recent Posts

Do Fish Get Tired Of Swimming?

Do Fish Get Tired Of Swimming?

Do Fish Get Tired of Swimming? Do fish get tired of swimming? This is a question that at first glance might seem like it has an obvious answer. However, when you really think about it, there is no obvious answer. So, now that your curiosity is piqued, let us find out...

Should a Fish Tank Be Covered?

Should a Fish Tank Be Covered?

Should a Fish Tank Be Covered?If you’ve recently become the proud owner of a fish, chances are you have a lot of questions regarding the proper care of your new pet. From the type of food it can eat to how often you should clean your tank. For many people, one of...


Submit a Comment

Your email address will not be published. Required fields are marked *