How Many Angelfish Can You Keep in a 40-Gallon Tank

To prepare an angelfish tank, you should know ‘How Many AngelfisH in a 40-Gallon Tank’. We all know that Angelfish are renowned for their beauty & elegance, making them a popular choice for freshwater aquarium enthusiasts.

But, knowing the optimal number of Angelfish housed in a 40-gallon tank can be confusing. Therefore, this article will help you learn the stocking density of Angelfish in 40 gallons, which requires careful attention.

If you want to learn everything that can keep your fish healthy, happy, and live long, read this article thoroughly. Before I tell you the factors that may influence the number of Angelfish and additional considerations required for Angelfish care, let’s first find out how many Angelfish are in a 40-gallon tank.

How Many AngelfisH in a 40-Gallon Tank

How Many Angelfish Can You Keep In A 40-Gallon Tank?

Keeping only 4-5 angelfish in a 40-gallon tank is best. As you increase the number of Angelfish in the tank, provide at least a minimum of 10 gallons per Angelfish in the aquarium.

Lower stocking density, like the 10-gallon guideline, provides better welfare & reduced competition among the fish living in a tank. You should also note that overcrowding may increase stress, aggressive behavior, and compromised water quality.

Always provide a minimum of 10 gallons of water per Angelfish in the tank to prevent this kind of issue. However, it doesn’t mean you should always follow the 10-gallon rule. It also depends upon your aquarium layout & structure.

You must divide the tank’s capacity by the space Angelfish requires. However, it is always best to stick with the 10-gallon guideline in a 40-gallon tank where you can accommodate a maximum of four Angelfish only to prevent overcrowding, aggression, and stress.

However, if you notice any of your fish exhibiting signs of aggression, stress, or chasing, you need to rearrange the tank or separate the suffering one. It is also important to consider factors that may influence the number of Angelfish you can keep in your tank. Therefore, let’s look at that quickly without wasting more time.

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3 Factors Influencing the Number of Angelfish

Size of Angelfish

Depending upon the size of the Angelfish, you must determine their space requirement. As larger Angelfish are known for vertical swimming patterns, they need more swimming space to encourage their natural behavior & foraging.

You should also know that adult angelfish can reach up to a size of 6 inches in body height and 8 inches in overall length. There is a significant relationship between the fish size & the tank size for various species, including Angelfish.

In major cases, angelfish’ often benefits from increased swimming behavior and avoids stress-related issues. Therefore, consider the potential size of the Angelfish you plan to have when determining the number of fish you can keep for your 40-gallon tank.

Tank Configuration & Filtration

Also, you will have to set up a suitable tank environment for the well-being of your Angelfish. You must provide adequate swimming space and incorporate hiding spots like plants, rocks, driftwood, or decorations that mimic their natural environment and offer security.

Also, install an efficient filtration system to maintain optimal water quality. In poor water quality, Angelfish are known to suffer from many health-related issues, including stress, poor metabolic rate, and death in rare cases.

A well-maintained filtration system will significantly reduce stress & improve overall fish health. Always remember to provide regular maintenance, including filter cleaning and water parameter monitoring, to ensure a healthy environment for your Angelfish.

Tank Mates & Compatibility

Now, you might be looking to select tankmates for your Angelfish to the visual interest and aesthetic look of your aquarium. If this is the case, you must consider tankmates’ compatibility & their social behavior.

Since Angelfish are known to be peaceful creatures, they can still become territorial during the Breeding season or when carding their fry. Therefore, you should avoid aggressive or fin-nipping species that stress or harm your Angelfish.

It’s best to always take with this suitable tank needs like gouramis, corydoras, catfish, etc. If you don’t pay attention to finding the best tank made for Angelfish, it will quickly lead to behavior problems & increase stress levels.

To know which fish must be avoided, consider reading our article on bad tank mates for Angelfish. Never mind taking the help of this article to select compatible tank mates & promote harmony within the tank ecosystem.

Additional Considerations for Angelfish Care

Additional Considerations for Angelfish Care

Water Parameters

Other things that you need to consider include water parameters. You must maintain an appropriate water perimeter for the health & livelihood of Angelfish. Central Marine Fisheries Research Institute studies have shown that deviation from optimal water conditions can harm their well-being.

The study also explored the influence of water temperature and pH level on angelfish stress responses. If you want to know more about It, consider reading our article on the ideal pH for Angelfish and angelfish water temperature requirements.

It is best to always keep the temperature range within 75-82 degrees Fahrenheit with a PH being slightly neutral to acidic ranging from 6.5-7.5, to reduce stress levels and promote better overall health.

Feeding Requirements

Talking about the feeding requirement of Angelfish, you must provide them with a balanced diet for optimal growth & nutrition of your pet. Some of many researches & articles can provide you with valuable insight into their feeding preferences and requirements.

You can check our articles on food for Angelfish share on this website. In general, you should be feeding a combination of high-quality flakes, pellets, and live or Frozen Food to provide the necessary nutrients for your Angelfish growth & vitality.

I highly recommend that you feed your adult angelfish at least 2-3 times a day, offering only what they can consume within a few minutes to avoid over-feeding and water pollution. It is best to clean the leftover or uneaten food to keep the water clean.

Tank Maintenance

Regular tank maintenance is very important to ensure a clean & healthy environment for your pet. If you follow up with proper tank maintenance, it will quickly lead to better water quality, degraded tank conditions, as well as various health issues.

You should know that regular water changes & tank cleaning can significantly affect angelfish health. You must follow up on routine water changes along with debris & algae removal to reduce stress levels and significantly improve fish health.

I advise you to perform a 20-25% water change every two weeks or conduct a regular cleaning to maintain optimal tank conditions.


After reading this article, you know that determining the optimal number of Angelfish you can have with a 40-gallon tank requires careful consideration, like tank size, fish size, tankmate compatibility, and water parameters.

Therefore I recommend you also do your own Research & study, which can provide you with more insights into these aspects to ensure the well-being of your Angelfish. However, if you follow the guideline in this article derived from hours & hours of Research, you can create a harmonious & thriving environment for your angelfish companion.

I have given my best to provide in-depth knowledge on how many fish you can keep in a 40-gallon tank. If you find this article helpful, then consider sharing it. Your share will not only help people learn ‘how many fish keep in a 40-gallon tank’ but also the factors that need careful consideration. Do check my other helpful guides on angelfish facts. See you in the next post, till then, take care & goodbye.