Angelfish Tank Size: How Many in 75, 55, 29, 25 Gallon Tank

Angelfish tank sizes vary from a few tens to hundreds of gallons. An overcrowded fish tank can suffocate or even kill your angelfish so it is important to stock the correct number of the pet fish in the right tank size to give them long and happy lives. So, what’s the best tank size for angelfish?

Keep one adult angelfish or two angelfish fry in a 25-gallon tank, two adult angelfish in a 29-gallon tank, 4 in a 55-gallon tank, and 6 adults in a 75-gallon tank. An adult angelfish is about 6-10 inches long while its fry is way shorter. A tank can carry more angelfish fry than adult angelfish.

Tank size (gallons)	Number of angelfish
20	One adult or two fry
30	Two adults or five fry
40	Three adults or seven fry
55	Four adults or ten fries
75	Five adults or ten fries
90	Seven adults or 12 fries

If you find your fish breathing fast or being sluggish and bored, it is possible that the aquarium is overcrowded. Angelfish require a lot of free space because they are active swimmers and love playing around the aquarium.

This article will provide proven tank size recommendations for angelfish and some signs that your tank is overcrowded.

Tank Size Recommendations for Angelfish

The optimal tank size for angelfish depends on your purpose for keeping the fish. You may need a slightly bigger tank when breeding them. Note that angelfish breed every four weeks. Therefore, a bigger tank is required for breeders to avoid overcrowding. If you are not breeding the angelfish, keep only male or only female angelfish in a tank.

Here are tank sizes and the number of angelfish you can keep in them:

20-gallon tank

A 20-gallon tank is the smallest recommended tank size for angelfish. Keep one adult angelfish or two angelfish fry in a 20-gallon fish tank. If you start with two young angelfish, they will eventually outgrow the 20-gallon tank. Within five months, the space will be crowded with two adult angelfish.

However, keeping the angelfish in pairs gives them companionship and allows the fish to play together. If you plan to keep more adult angelfish, you will have to purchase a larger tank. Otherwise, reduce the angelfish population in your 20-gallon tank to the recommended threshold.

Do not use a 20-gallon fish tank for breeding angelfish. Instead, use a bigger tank – at least 70-gallons. Breeding angelfish in a 20-gallon tank will cause overcrowding and poor filtration. Also, the small tank size means you cannot put more aquarium plants or decorations inside the tank.

When it comes to maintaining a 20-gallon tank, it’s much easier than a larger tank. A 20-gallon tank is small and easy to clean. When cleaning the tank, remove the fish and put them in a container with the same water parameters.

Use a paper towel or a clean cloth to wipe inside the tank and remove all the dirt. Avoid using soaps or chemicals to clean your fish tank. They might cause pollution and lower your angelfish activity.

30-gallon tank

A 30-gallon tank is a bit heavier than a 20-gallon tank. Place the tank with angelfish in your living room as part of your house decoration. Keep two adult angelfish or five angelfish fry in a 30-gallon tank. The fish will have enough oxygen and space to swim and play.

A 30-gallon tank is also relatively small for breeding angelfish. Like the 20-gallon tank, a 30-gallon angelfish tank is suitable for beginners. The aquarium has a little space for adding plants and decorations. Ensure that the rocks and plants in your tank are smooth with no sharp edges that can harm the fish.

A 30-gallon tank is slightly heavier than a 20-gallon tank. When cleaning a 30-gallon tank, you should handle it with care. Clean and remove food leftovers from inside the tank to avoid decomposition and accumulation of toxins.

A 30-gallon tank needs regular water changes. Changing more than 70% of the water at once can destabilize the water parameters and harm your angelfish. Change 30% of the water every two weeks to improve water and oxygen filtration for your angelfish.

40-gallon tank

Angelfish are highly aggressive, territorial, and take a lot of space. Therefore, a 40-gallon tank can accommodate four adult angelfish or up to seven young angelfish. As the young fish grow, you will need to transfer some of them out of the tank to create room for the ones remaining.

Since angelfish are aggressive and very territorial, they always fight for dominance when placed with other types of fish. Avoid keeping multiple fish species in a 40-gallon tank. With a 40-gallon tank and two pairs of adult angelfish, you will be able to care for the fish adequately.

Decorate the tank using plants and rocks to give your angelfish multiple breeding, hiding, and playing spaces. Grow plants like the Amazon sword plant in your fish tank because they are native to the angelfish environment. The plant is also a natural carbon sink for your aquarium.

Unlike smaller volume tank sizes, maintaining a 40-gallon tank is quite challenging since it holds more fish and decorations. Clean the tank every month, remove accumulated debris, and change 30% of the water to create a fresh environment for your angelfish.

55-gallon tank

A 55-gallon tank gives angelfish enough oxygen and space to thrive. The tank is spacious enough for breeding angelfish. It is recommended to keep up to five adult angelfish or up to ten young angelfish in a 55-gallon tank.

Although, there is much debate about it, breed male to female angelfish in the ratio of 1:3. That will keep the angelfish balanced and suppress male aggression.

A 50-gallon tank is huge and heavy, so, it’s difficult to move the tank from place to place inside the house. While deciding the appropriate location for a 55-gallon tank, ensure the area does not receive direct sunlight. Also, choose a location that’s free from traffic to prevent stressing your fish.

Direct sunlight promotes excessive algal growth in the aquarium.

A 55-gallon tank holds many angelfish. Therefore, you cannot remove them from the tank when cleaning. Only change 25% of the water twice a month to keep your angelfish healthy and happy..

75-gallon tank

Just like a 55-gallon tank, a 75-gallon tank is heavy and fragile. The tank can hold up to seven adult angelfish or ten angelfish fry. This tank has enough space to accommodate angelfish tankmates such as mollies and dwarf gourami.

Since angelfish have dominant behavior, ensure that the tankmates are safe inside the tank by adding enough substrates. Aquarium decorations such as wood and fine stones are essential for keeping angelfish comfortable in a 75-gallon tank. With this tank, you can also breed male and female angelfish in the ratio of 1:3.

A 75-gallon tank requires greater maintenance. The fish will need adequate food and plenty of plants for breeding and hiding places. These tanks also require structural support at a strategic place in your home because you cannot move them frequently. For a large tank, use artificial lighting or indirect natural light.

The plants you grow inside a 75-gallon tank also need maintenance. Clean and prune dead branches and leaves. Because of the tank’s large size, clean it and change the water without removing the angelfish. I highly recommend an aquarium filter for a 75-gallon tank for improved filtration and bacterial control.

You don’t need a bigger tank unless you are breeding the angelfish. If you are new to ornamental fish keeping, start with a 20 – or 30-gallon angelfish tank. However, a 75-gallon tank is best for breeding angelfish. It can accommodate the breeding fish rations and the young ones once they are born.

Minimum tank size for angelfish

The minimum tank size for angelfish is 20 gallons. Angelfish love swimming and playing at every level of the aquarium. A 20-gallon tank is enough to keep a single adult or two small angelfish happy. Keeping more than that will mean less space, increased competition, aggression, and reduced oxygen in the water.

However, to provide optimal conditions for your angelfish, get a 40-gallon tank. Although the tank is quite small, it’s easy to clean and reposition around the house. It is also easy and cheap to feed a few fish in a 40-gallon tank.

Signs your aquarium is overcrowded with angelfish

Here are some signs that your aquarium is overcrowded with angelfish:

Inactive angelfish

Angelfish are aggressive swimmers. If they start lying around more often and swim less, it could signify an overcrowded aquarium. Overcrowding increases water toxicity from fish waste and food leftovers. Eventually, it reduces oxygen concentration in the water and lowers angelfish activity.

Stunted growth

Angelfish should grow by at least two inches every month. Are your angelfish the same size for many months? The chances are that their growth is stunted. When angelfish are overcrowded, their growth slows down because they compete for food and essential resources. Aquarium diseases caused by overcrowding also result in stunted angelfish growth.

Frequent increases of ammonia and nitrates in the water

Overcrowded angelfish produce a lot of waste and leave behind many leftovers that decay inside the tank. The decomposition produces and accumulates ammonia and nitrate inside the tank. Always use an ammonia test kit to determine your aquarium ammonia levels.

Angelfish breathing fast

Overcrowded fish can be stressed in many ways. They become aggressive to each other, lack oxygen, and constantly live in fear. The fish also have no space to swim freely. Therefore, overcrowding hurts angelfish and increases their breathing. Use a filter or change half of the aquarium water when you notice this.

Frequent diseases in the aquarium

When you see your fish getting sick and dying more frequently, it’s a sign that your aquarium is overcrowded. The most common symptom of sick angelfish is dark spots on the body. You need to observe them keenly to distinguish the spots.

Even when the fish are treated, the disease recurs, which is a major sign of an overcrowded aquarium.

Always observe the behavior of your angelfish whenever food is introduced to them. Slight changes in their bodies, activity and feeding behavior could mean overcrowding.