The Best Community fish for a 40 gallon tank

Best fish for 40 gallon tank

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The Best Community fish for a 40 gallon tank

When choosing the best fish for a 40-gallon community tank, research the natural home and behavior of desired fish species and choose tank-bred or captive-bred fish that are compatible and can comfortably fit in the tank. Ensure the tank has the right filtration system for the size and pick fish that are hardy, easy to care for, and provide enough space for each fish. In this guide to the best community fish for 40 gallon tank it is best to focus on species that prefer similar water parameters.

Adding fish to your aquarium can be an exciting experience. When choosing fish for a forty-gallon tank, it’s important to consider how compatible they are with each other and how well they will do in a particular environment. One of the best groups of community fish for a forty-gallon tank is the Rasbora family, which includes Harlequin Rasboras, Neon Dwarf Rasboras, and Celestial Pearl Danios. These fish tend to be peaceful and thrive in shoals, so having a group of these will bring a lot of joy to your tank.

Tetras are another excellent choice for a forty-gallon tank. Both small varieties like the glowlight tetra and larger species such as the black skirt tetra will do well in the tank. They tend to be peaceful and active, and the bright colors of their scales can add to the decor of your tank.

Finally, many types of catfish can do well in a forty-gallon tank. Corydoras cats and bristlenose plecos are great for hobbyists, as they help keep the tank clean and tend to be peaceful. They should be kept in groups of five or more. When choosing fish for a forty-gallon tank, it’s important to consider the size and compatibility of the species, as well as the requirements for each individual fish. Once you’ve chosen the perfect community for your tank, you can look forward to enjoying it for years to come.

The best community fish for a 40 gallon tank

Cherry barb
Cherry barb

Due to their popularity among aquarists, the Cherry Barb has been listed as vulnerable on the IUCN Red List. This is due to overharvesting, as well as the dwindling quality and availability of their natural habitats. Therefore, it’s important to practice responsible tank stocking when considering these fish as pets.

If you’re interested in owning Cherry Barbs, here are some tips for making the best decision for you and your tank:

• Start small – Add a group of no more than six to your tank to start with and observe how they interact before adding any more, especially if you’re new to owning this species.

• Water parameters – Make sure that the pH, temperature, and hardness levels are suitable for this species.

• Tank mates – Select other fish that are of similar size and temperament to the Cherry Barbs, making sure to avoid anything that might be aggressive or overly enthusiastic.

• Diet – These fish are omnivorous, so they’ll happily nibble on a range of beginner-friendly flakes and pellets. In conclusion, the Cherry Barb is an ideal fish to own both in terms of looks and care requirements.

As long as you practice smart tank stocking and look after them properly, these fish are sure to bring life and color to your aquarium.

These fish are known to be peaceful and tolerant when it comes to their tankmates. They can easily be combined with a range of other freshwater fish species, regardless of their size. Thus, Cherry Barbs make an excellent addition in a diverse aquarium community.

8. Glass Catfish

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Glass catfish

Glass catfish are a great addition to any freshwater tank due to their low-maintenance nature and active behavior. With their striking translucent bodies, they make for a unique and eye-catching addition. Adding other tank mates to your community tank is easy and hassle-free as long as you keep away from large and aggressive species. Glass catfish will thrive in a well-maintained aquarium, keeping your tank lively and vibrant.

9. Guppies

Guppy fish are an incredibly popular freshwater fish in the aquarium scene, sporting gorgeous tailfins filled with color! Low-maintenance and beginner friendly, these fish have a minnow-like profile with a pointed snout and upturned mouth. With luck and genetics, the guppy fish lifespan can be between two and five years, with adults reaching up to two inches in length. Appropriate tank size would be at least a five-gallon tank, but preferably a 10-gallon tank or larger. The best environment for guppies would be one with a water temperature of 64°F to 84°F, pH level of 7.5 to 8.0, and water hardness of 8 to 12. When it comes to decorations, guppies aren’t picky and prefer natural items whenever possible.


Guppy fish are an ideal choice for those looking to start their own fish-keeping tank, as they are well-suited to peaceful multi-species tanks. These small fish possess vibrant fan-like tails in a variety of colors, making them an aesthetically pleasing addition to any aquarium. Guppies tend to swim towards the top of the water and do best in tanks with plenty of vegetation. Furthermore, breeding is easy, since guppies are livebearers and the fry are born fully-formed.

5. Cardinal Tetra

The cardinal tetra is my go to pick for a community fish that prefers to hang out in the middle of the tank, they prefer to stay in schools so it is always best to make sure you have at least four to six in your tank.

cardinal tetra fresh water community fish
Cardinal tetra

The cardinal tetra is a popular and pretty fish often kept in community fish tanks, this small fish is known for its bright blue and red stripes along its body, making it a beautiful addition to a clean tank with a dark background. Cardinal tetras are peaceful and are best kept in a tank with other small, friendly fish.

Taking care of cardinal tetras is not difficult, making them a good option for new fish tank owners while they are a tough fish that can handle life in a tank and will do well with proper filtration and water quality. Neon tetras like water that is between 72-82°F and have a pH between 6.0-7.0. They eat a mix of things, including flakes, pellets, and small live or frozen foods.

When kept in the right environment, cardinal tetras are lively and social, adding a pop of color to any tank. With their peaceful nature and easy care, neon tetras are a great choice for a 20-gallon tank and will fit in well with other similarly sized fish.

2. Cory Catfish

Cory catfish, also known as Corydoras, are a popular species of tropical fish that do very good in community aquariums. These small, bottom-dwelling fish are known for their gentle and peaceful nature, and for keeping the bottom of tanks clean, making them an ideal addition to a community tank. Cory catfish have a distinctive, armored body with hard spikes and come in a variety of colors, that can include albino, spotted, green, and black.

Cory Catfish
Cory Catfish

Taking care of Cory catfish is easy because, Cory catfish are hardy and easy to feed, making them a good choice for both beginner and experienced aquarists. They are well-adapted to community life and thrive in a well-cycled tank with proper filtration and water quality. Cory catfish prefer water temperatures between 72-78°F with a slightly acidic to neutral pH between 6.0-7.5. They are omnivores and will feed on a variety of foods including flakes, pellets, and small live or frozen foods.

Cory catfish play an important role in maintaining the health of an aquarium by scavenging for food and cleaning up waste. They are also active and social fish that will add both interest and liveliness to a community tank. With their peaceful nature, hardiness, and ease of care, Cory catfish are an excellent choice for a 20-gallon community tank and make an ideal addition to any community of similarly sized fish.

3. Otocinclus

Otocinclus catfish, also known as “otos,” are a species of small algae eating fish that are kept in aquarium to clean up and control algae. They are known for their peaceful and hardy nature, which makes them an ideal addition to any community tank with bettas. Otocinclus catfish have a slender, brown or black body and are known for their ability to clean algae from aquarium plants and surfaces.

Otocinclus catfish
Otocinclus catfish

In terms of care, otocinclus catfish are easy to take care of and is well-adapted to captive life. They prefer a well-cycled tank with proper filtration and water quality and some live plants. Otocinclus catfish require water temperatures between 72-82°F and a slightly acidic to neutral pH between 6.0-7.5. They are strictly herbivores and require a diet consisting mainly of algae wafers or blanched vegetables.

Otocinclus catfish can play an important role in maintaining the health of an aquarium by keeping surfaces of the aquarium and plants free of algae.

6. Shrimp

Freshwater shrimp are a popular addition to many aquariums due to their interesting appearance and behavior. They come in a variety of colors, including red, green, yellow, and brown, and are known for their active, cleaning behavior. Freshwater shrimp are also a great source of food for other fish in the tank, making them a valuable addition to any community.

red shrimp
Red shrimp

Taking care of freshwater shrimp is relatively easy, making them a good choice for both new and experienced fish tank owners. They require a well-cycled tank with proper filtration and water quality. Freshwater shrimp prefer water temperatures between 68-82°F and a slightly acidic to neutral pH between 6.0-7.5. They are omnivores and will feed on a variety of foods, including pellets, flakes, and small live or frozen foods.

Freshwater shrimp are social creatures and do best in a tank with other friendly fish. They are also good for people who want to breed fish because they are easy to breed in captivity. With their active behavior and ease of care, freshwater shrimp are a great addition to a 20-gallon tank and will fit in well with other similarly sized fish.

4. Kuhli Loach

Kuhli loaches make excellent tankmates for your betta fish! These eel-shaped beauties are peaceful, and do a great job of cleaning up leftover food in the aquarium. Although they can be a bit shy, they add a ton of personality to the tank. A must-have for any aquarist looking to add an extra bit of life and color to the aquarium!

Kuhli Loach

The Kuhli Loach (Pangio kuhlii), also known as the Coolie Loach or Leopard Loach, is an Old World fish from the Cobitidae family. Originating in Southeast Asian freshwater streams, such as Malaysia, Thailand, and Borneo, the Kuhli Loach was first classified in 1846 and was used historically as a source of food in Indonesia.

4. Harlequin Rasboras

The peaceful, 2-inch Rasbora is ideal for beginner fish keepers. These fish feature an eye-catching orange body with a black triangular patch that adds to its attractive appearance. To ensure a healthy and happy school of Rasboras, it is recommended to buy at least six. These gentle fish get along with other tankmates, including Bettas, and provide great exercise and enrichment for them as they’ll attempt to chase the Rasboras without much success. To learn more about caring for Rasboras, take a look at our full care guide.

Harlequin Rasboras for tank

The Harlequin Rasbora is a fish with an orange-pink body and a large, triangular black pattern on its back, extending from the midpoint of its dorsal fin towards its caudal peduncle. The tail fin is red on the outer rays and hyaline on the inner part. The pectoral and pelvic fins of the Harlequin Rasbora are found in a common cyprinid pattern, the pectoral fins sitting behind its operculum, and the pelvic fins forward of the dorsal fin.

A mature Harlequin Rasbora measures up to 2 inches (5 cm) in length. Males tend to have a slightly bigger black patch and a more rounded marking at the anal fin while ripe females have a fuller body outline.

Species of fish similar to the Harlequin Rasbora are Trigonostigma espei and Trigonostigma hengeli, which were once considered subspecies. These fish have a more slender body shape, and the black marking is replaced by a horizontal strip tapering to the caudal peduncle, thickened and extended below the dorsal fin. This marking pattern is also known as a lamb chop, due to its resemblance to the cut of meat.

3. Ember Tetras

Adding these red-orange tetras to an aquarium of at least 10 – 20 gallons can give it a lively, vibrant look. You should try and get a school of at least five or six to reduce the chance of the predator picking any of them out. These peaceful fish typically swim around the middle of the tank and consume the same food as the other herbivores, simplifying their care.

ember screencap

The Ember tetra fish is a brightly colored type of fish that is often kept in aquariums. They require a minimum tank size of 10 gallons with a few live aquarium plants. The water should be lightly acidic and around a pH of 6.6, with temperatures ranging between 73 and 84 degrees Fahrenheit. To keep them healthy and happy, the tank should have a darker substrate and plenty of live plants, as the Ember tetra is quite fond of swimming through them.

When purchasing Ember tetras, it’s best to get a group of at least 6, though the recommended group size is 9-10. Tetras should also be kept with other types of tetras, such as the neon tetra, though they should not be kept with fish significantly larger than them. These fish swim mainly in the middle level of the aquarium and prefer to feed on food located there rather than on the bottom of the tank. To avoid any leftovers, it is recommended that Ember tetras are kept with bottom feeding fish such as pygmy corydoras.

Ember tetras are relatively easy to care for and can be fed a variety of food, including flake, frozen, and freeze-dried foods. To really bring out their colors though, it is a good idea to also provide them with live foods such as worms and brine shrimp. If a well-maintained aquarium is provided for them, Ember tetras can potentially live for up to 10 years or more.

What to consider when picking the 5 best community fish for a 20 gallon tank

A 20 gallon tank is big enough that you can add bigger fish and more fish to the tank, you still want to be careful not to overstock the tank right away before it has a chance to establish the bio load management in it.

1. Size of the fish

The size of the fish can be important when selecting the 5 best community fish for a 20 gallon tank. You want to choose fish that are all similar in size to one another so one species does not bully or consider another species food.

2. Water Chemistry

Different species of fish prefer different water parameters and it is important to find fish that prefer the water the same temperature and the same hardness.

3. Diet and feeding habits

Having fish that have the same diet will make it easier to feed your fish the proper diet. If your fish are carnivores it is important to make sure all the fish are carnivores or at least omnivores. And the same holds true for herbivores.

4. Temperament and compatibility with other fish.

The temperament of each fish species can be different and it is important to find fish that have a similar temperament and chemistry. This will help with the compatibility with each fish and how they interact with each other.

Pro Tip

Choose fish based on where they prefer living in the tank.

The tank can be broken up into 3 zones; top, middle, bottom.

Top half of the tank: Some species of fish like guppies prefer the top half of the tank because in their natural environment they feed on the surface of the water.

Middle of the tank: Some species on the other hand like tetras, angel fish, and cichlids prefer the middle of the tank.

Bottom of the tank: Bottom of the tank feeders are going to be your traditional bottom feeders like cory catfish and plecos. These fish are scavengers and feed primarily on the bottom of the tank in the substrate.

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Lee Johnson

Lee Johnson

Aquarium Enthusiast

I love sharing my knowledge about all things aquarium related. I have been keeping aquariums for over 20 years and cannot imagine a life without an aquarium. 

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