As with many other things in life, the key to managing a fish tank is balance. Too many inhabitants in the aquarium will affect the health and happiness of the fish. Luckily, you can actually find out how many fish you can fit in your tank easily. But remember, the little fish will grow up! To help you, this article has answered some of the frequently asked questions about the number of fish that can be accommodated in an aquarium.
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Method 1 of 7: How many fish can be put in the aquarium at a time?
Step 1. Try to provide about 4 liters of water for every 3 cm of fish
While there are many different types of fish, each with different needs, you can use this general rule to give your fish enough space to move around in the tank. More swimming space makes fish healthier and happier. This calculation is also very good for keeping the aquarium clean and preventing the buildup of harmful substances (such as ammonia and nitrates) that can kill fish.
For example, if you have an aquarium with a capacity of 80 liters of water, and you want to add some broom fish (glass cleaner) about 10 cm in size, you can add 5 broom fish to the tank
Method 2 of 7: What happens if I put too many fish in the tank?
Step 1. The aquarium becomes easily dirty and dangerous for fish
Too many fish will produce a lot of waste, which makes the aquarium dirty and difficult to keep clean. Also, too much fish will produce excess ammonia, which can make the fish sick or die if the levels are too high.
- Even if you have installed a high-strength filter designed to neutralize ammonia, there are still high levels of nitrates in the aquarium which can compromise the fish's immune system, making it more susceptible to disease and spread.
- Fish will also feel very stressed if they don't have enough room to swim. This can interfere with the immune system and overall health of the fish.
Method 3 of 7: How many fish can be put in a 20 liter tank?
Step 1. Depending on the size, you can add about 4 to 6 fish
We recommend that you do not include fish that are more than 13 cm in total. To find the total length of all the fish, add up the lengths of the fish you want to add to the tank. However, keep in mind that if you add small fish, they will grow larger and fill the tank.
- In general, fish that can grow larger than 5 cm should not be placed in a 20 liter tank. The fish will not have enough room to swim and have fun.
- A 20 liter aquarium is perfect for small fish like tetras, guppies or bettas.
- However, never include more than one betta fish. These fish are very territorial and will fight if several fish are placed in the same tank.
Method 4 of 7: How many fish can be put in a 40 liter tank?
Step 1. Depending on the size, you can add about 5 to 10 small fish
If you're new to an aquarium, it's a good idea to start with small fish. Once your fish-keeping skills have improved and the aquarium has developed into a clean and healthy environment, you can add up to a maximum of 20 small fish as long as they fit in the tank.
- Some of the fish that can breed in a 40 liter capacity aquarium include tetra, corydora, mini gourami, and guppies.
- Remember, some small fish can grow up. For example, a small goldfish can grow up to 15 cm in one year.
Method 5 of 7: How many fish can be put in a 200 liter aquarium?
Step 1. You can put fish no more than 140 cm in total
Having an aquarium with a large size is certainly fun because you can create a beautiful underwater environment. However, the key is not to overfill the tank and stress the fish. Always follow the general "4 liters for 3cm fish" rule, and don't add too much fish.
For example, you might include 10 small guppies, 5 broomfish measuring 10 cm, 5 rainbow fish each measuring 5 cm, and 3 parrotfish measuring about 13 cm
Method 6 of 7: What is the lucky number for fish?
Step 1. The number 9 is used as a symbol of prosperity in feng shui
It is considered a lucky number, symbolizing wealth and a long and happy life. Many people who believe in or practice feng sui keep 9 fish in their aquarium or fish pond to channel this positive energy.
According to feng sui, the best combination to do is to keep 8 goldfish and 1 arowana, which symbolizes good luck
Method 7 of 7: Is there an online calculator that can be used to calculate the ideal number of fish in an aquarium?
Step 1. Yes, you can visit
Use this online calculator if you want to find an easy and accurate way to calculate the number of fish you can put in your aquarium. Enter the required information, such as fish size, aquarium specifications, and the type of water you use in the aquarium to get an estimate of the number of fish that can be accommodated.
