Best Freshwater Aquarium Fish Combination 

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  • Updated on: 19/05/2020

what is the best fish combination for a freshwater aquariumPhoto by Shaun Low on Unsplash

Compatibility of aquarium fish is an important question that arises for many aquarium owners. If you are a beginner or even an experienced aquarist, you will still worry about the compatibility of fish with each other.

There is a lot of discussion and controversy around the theme of compatibility of aquarium fish. Choose fish carefully, because their life and your comfort depend on your choice. Before you go to the pet store, study all available information about the fish you like.

Basic Rules for Selecting Aquarium Fish

Full compatibility or incompatibility of fish is due to the following features:

  • Family, group, a suborder of fish;
  • The size of the fish;
  • Parameters of aquarium water and fish-keeping conditions.

If you combine fish from the same family or approximately the same size in the aquarium, or with identical conditions of maintenance, this will serve as a guarantee of success! 

The main mistakes in the aquarium population are the following:

  • Overpopulation of the aquarium. Every aquarium pet should live in comfortable conditions. Overpopulation of the aquarium is a direct path to fights, injuries, and death of any fish, even peaceful ones.
  • Non-compliance with the conditions of maintenance and zoning of the aquarium. To keep fish, you need to take into account their specifics, their characteristics, and character.
  • Improper maintenance of fish, which leads to distressing consequences. In bad conditions, fish begin to fight for survival and die.
best freshwater aquarium fish combinationPhoto by Renate Helgerud on Unsplash

Compatibility of Fish by Environmental Parameters

There are cold-water and warm-water fish; there are fish that like soft water, and fish that like hard water. There are fish that need thickets of living plants, and there are fish that tear, dig up, and eat all the plants in the aquarium.  

There are several parameters: the requirements for lighting and the speed of water flow in the aquarium. There are fish that love standing ponds, and fish that live in rivers with a fast current of water. You must consider the degree of water salinity, etc.

Compatibility of Fish by Size 

It is recommended to keep large fish together and to keep small fish with other small fish. Even the most peaceful fish will not miss the opportunity to eat another fish that fits in its mouth.

Some aquarists believe that if a large fish is put in the aquarium as a baby, then when it grows up, it will not offend its smaller neighbors. 

Compatibility of Fish by the Nature of Food

There are herbivorous fish and predatory fish. Any herbivorous fish will not refuse animal food, such as a moth. The characteristic of herbivorous fish is that their ventricle is small, their intestines are long, and they are adapted for digesting plant food.

If these fish are often fed with a moth, eventually they will have problems with digestion and liver.

Predatory fish should not be kept in the same aquarium with small and peaceful fish. The predator will hunt any fish that it can swallow.

Compatibility of Fish by Behavior

Some fish are very aggressive, and aggression is especially manifested during mating games, spawning, and caring for offspring. They should never be combined with peaceful, small fish.

When choosing fish by the nature of their behavior, do not forget that many fish like to hide in shelters. It is necessary to ensure that the aquarium has shelters in the form of grottos and caves. 

For some fish that like to burrow into the ground, the fraction of the soil and its processing is important.  For such fish, sand with rounded edges is preferable.

You cannot adhere to only one of the compatibility parameters when choosing fish. It would be best if you observed them in a complex.  

Best Freshwater Fish for Your Home Aquarium

To make it easier for you to create your first aquarium, we have compiled a list of the best aquarium fish for beginners. All of them are distinguished by their unpretentiousness, tolerance for conditions in the aquarium, peaceful nature, convenience for life, and modest size.


guppy fish for best freshwater aquarium combination@sakda_nokkaew / FreePik

Guppies are very unpretentious, get along with others, and reproduce. They are viviparous, which means that the alevins immediately swim and are adapted to live. But if you leave a young fish in a common aquarium, it will quickly be eaten; you need to catch them in a separate container.

It is very simple to breed them; it is enough to keep males and females together. Guppies eat all kinds of food.

Swordtails, Mollies and Platies

swordtails mollies and platies for freshwater aquarium combination

These fish are very similar in behavior and in environmental requirements, although they are very different in appearance. Just like guppies, they are viviparous. 

They reproduce very quickly; the principle is the same as in guppies: keep the males and females together. They are very bright and mobile fish, and they are tolerant of various conditions in the aquarium.

In general, they are similar to guppies in terms of environmental requirements, but outwardly, they are larger and have a variety of colors and body shapes. Just do not buy a lot of male swordsmen in one aquarium; they will fight!

Danio Rerio or Zebrafish

danio rerio for best freshwater fish combination

Danio Rerio is a small elegant fish. For its small size, peaceful disposition, and unpretentiousness, it has gained great popularity among owners of aquariums.

These fish need to start 5-6 pieces at once, as they live in flocks. The Danio must have a free place to swim at the surface, as it is a very mobile fish.

Danio Rerio are omnivores; they eat any kind of food: artificial, live, frozen. Breeding Danio is very easy; the female lays from 200 to 500 eggs at once.

Cardinal Tetra


This is a small and very unpretentious fish. At the same time, it is brightly colored, gets divorced and is completely non-aggressive.

They tolerate cold water well; they can even be kept in a pond in the yard in summer. They like to move in the middle layers, and they also like to gather in flocks. 

You need to keep them in small flocks from 6 pieces. Although it can be large, with its modest size, cardinals do not require large aquariums. With good maintenance, they can live up to 3 years.


Corydoras best freshwater aquarium fish combination@chemmie1976 / Pixabay

These are small, mobile, beautiful and gregarious catfish. There are many different types of Corydoras, but the most popular are the speckled catfish and the golden catfish.

All of them are similar in their behavior: living on the bottom, they are constantly looking for food remnants, thereby cleaning the aquarium. Any type of food is suitable for feeding, but it is important to make sure that the food falls to the bottom, and the catfish do not remain hungry.

Keep Corydoras in flocks. They are very interesting to watch.

Harlequin Rasbora

This is a very beautiful little fish that gets along well with all of the above fish.

Keep rasbora  in flocks, and the aquarium should have enough free space for swimming. Flocks of rasbora will decorate any aquarium.

You can use a variety of feed, but it is important not to give large particles of food, as this fish simply will not be able to swallow them.


acanthophthalmus for best freshwater aquarium fish combination

This is one of the most unusual fish an inexperienced aquarist can get. This fish resembles a small snake, but this fish is completely harmless. 

Acanthophthalmus often hide during the day. In order to feel comfortable, they  need shelter and soft ground, in which they like to dig. Acanthophthalmus help keep the aquarium clean by eating everything that falls to the bottom. 

Cherry Barb

These are peaceful, small fish, the males of which are very bright in color, for which they got their name.

This fish lives in a flock, so you need to keep up to five of them. The size of the cherry barbs is small; the color of the males is bright red and very noticeable. The requirements for maintenance are low.


ancistrus is the best fish for freshwater aquarium combination@creativetraeme / Pixabay

This fish has earned its popularity for its unusual appearance and for cleaning the aquarium. Ancistrus is a catfish. This fish lives by eating algae and fouling.

Last Words

Of course, this is an incomplete list, and it can be increased many times. But for novice aquarists, these fish are perfect. 

First of all, before installing the aquarium, find out all about the fish you like. Choose first of all hardy, easy to care for, and peaceful fish that get along well with others in the general aquarium.

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