Freshwater fish live in inland lakes, rivers, streams, and wetlands with very low saltwater (salinity) levels; often less than 1.05%. Freshwater fish may spend a portion of their entire lives in freshwater.
Freshwater fish have gills, scales, and other internal organs that are adapted to preserve or reclaim salts in their bodies to make up for lack of salt in their environment.
Freshwater fish are the most geographically concentrated fish species, they constitute almost half of fish species on the planet but live in less than 3% of the earth’s water systems. The number of freshwater fish species worldwide is over 15,000.
Freshwater fish is an important source of food to a large number of the world’s population. Rich in protein, the freshwater fish account for 6% of human protein supplies worldwide. Almost 94% of freshwater fisheries are located in developing countries all over the globe, employing millions of people.
The biggest threat to freshwater fish is human activity. Pollution, loss of natural habitat, overfishing, dams, and introduction of invasive fish species has resulted in the extinction of several freshwater species, while pressure is being put on existing freshwater fish.
Anadromous or Migrating Fishes
Anadromous fishes are known as migrating fishes. These are fish that hatch in freshwater rivers and streams, but migrate to the ocean to live their adult lives before returning to freshwater to breed. e.g trout and salmon.
On the other hand, fish that hatch in the ocean, but live their adult lives in freshwater rivers and streams before returning to the ocean to spawn and hatch are called catadromous fishes.
Classification of Freshwater Fish
Freshwater fish are classified by the water temperatures in their native environments. These are:
Coldwater fish are fish that survive at 10-16°C water temperature. The coldwater streams, rivers, and lakes are rich in oxygen, and coldwater fishes are distinguished by their big sizes. Trout is a cold-water fish.
These are freshwater fish species that survive at a water temperature of 10-20°C, examples of cool water fish are Moss Cologne and Yellow Perch.
These are freshwater fish species that survive in water conditions of 27°C. Warm water fish can adapt to cold water conditions, but they flourish in warm, and tropic water temperatures. Examples are Catfish Bluegill and Crumpets.
What are the characteristics of Freshwater Fish?
Since freshwater fish live in waters with low salinity levels, they have highly developed adaptive mechanisms enabling them to breathe, feed, breed, and avoid natural predators. We will outline a few of these characteristics below.
Unlike seawater fish, the freshwater fish gills function as a filter, preserving salt inside the fish body, while preventing impurities.
Some freshwater fish like the betta fish, have labyrinth organs that enable the fish to breathe oxygen at the water surface and use their gills primarily for excreting waste products.
Due to the low saline levels in the freshwater being absorbed, the freshwater fish kidneys prevent excessive salt loss by reabsorbing salt from fluids being excreted from the body.
Longer Dorsal Fins
Freshwater fish have longer dorsal fins that stretch more than half across the back. They also have round-shaped fins.
Can freshwater Fish live in Aquariums?
The answer is a resounding yes! Freshwater fishes are ideal aquarium creatures, and they thrive in confined environments.
Most freshwater fish species are either solitary swimmers or the schooling type, and they are highly recommended for both rookies and skilled aquarium keepers.
Freshwater Fish Diet
Domestic freshwater fish can be fed a diet of commercially available fish pellets, and flake foods. To increase the freshwater fish protein nourishment, frozen or freeze-dried bloodworms, and shrimps (Mysis & Brine) are recommended.
Whether keeping a solitary or community freshwater fish tank, freshwater fish should be fed once or twice daily, with food that must be eaten within a couple of minutes.
Water and Tank Maintenance
Freshwater fish thrives in tropical water temperatures of 72-82°F, with an average pH of 7.0. However, most freshwater fish may tolerate pH levels of 6.8 to 7.6. To maintain these water parameters, half of the tank water volume must be changed twice-monthly, and water temperature must be checked twice a week.
Whether you desire a solitary, or inclined towards a community tank, the minimum tank size for freshwater fish is between 5 to10 gallons. The tank must be equipped with filters, a heater, and must have lots of plants providing cover.
This way, your freshwater fish (or fishes) has lots of places to hide, and space to swim happily. By having different freshwater fish species in a tank, your aquarium will come alive as freshwater fish in a community tank will occupy all levels of the tank, and brightly colored schooling fish of the same species will be a pleasure to watch.
List of Aquarium Freshwater Fish Types
Different freshwater fish types can be successfully kept as pets in household aquariums. However, not all freshwater fish require the same levels of care and attention.
Like all domestic pets, freshwater aquarium fish owners need to have certain levels of experience to successfully care for them. Some freshwater fish require minimal experience, some do not.
Below is a list of some freshwater fish suitable for all tanks, grouped by the level of experience fish owners require to care for them.
This is a great fish for rookie fishkeepers. The Fire Mouth cichlid gets its name from the red color of its scales during its breeding period.
They are cheap, popular, and can be found at your corner pet store. Fire Mouth cichlids can be kept in a 30-gallon community tank with similar sized fish.
FireMouth Cichlid Fish Facts
|Aggressive||Territorial during breeding|
The Neon Tetra is a colorful fish with iridescent stripes across its middle. They are easily cared for and adapt easily to various aquarium environments.
During breeding, the Neon Tetra will require a separate aquarium with little lighting. Their diet consists of commercial fish flakes, and vegetables. They can also be fed live and frozen foods.
Neon Tetra can easily live in a community tank with other freshwater fish, but care should be taken to select non-aggressive tank mates. The recommended minimum tank size for this fish species is 10 gallons.
Neon Tetra Fish Facts
Guppies are a favorite of aquarium keepers worldwide. They are easy to keep, and easily adapt to different environments.
Guppies can be fed a diet of fish meal and flake food, which should be complemented with a protein nutrient of Blood worms and Brine shrimp. A peaceful fish, Guppies can cohabit with other freshwater fish in a community tank. The recommended minimum tank size for Guppies is 10 gallons.
Guppies Fish Facts
|Size||0.6 – 2.4 inches|
|pH||6.8 to 7.8|
The Zebra Danios requires minimum care and attention. It can be fed a diet of commercial fish flakes, supplemented by live or frozen foods.
The Zebra Danios is a peaceful fish and can cohabit with non-aggressive freshwater fish species. The recommended minimum tank size for Zebra Danios is 10 gallons.
Zebra Danios Fish Facts
The Molly fish is recommended for aquarium rookies. They are widely available in pet stores and easily cared for. Millie’s can be found in different colors.
Molly fish are livebearers, and parents will probably eat their young. Mollies can be fed commercially available fish flakes and vegetables.
Mollies are peaceful and can live with other freshwater fish in a 20-gallon community tank.
Mollies Fish Facts
Easily distinguished by their sword-shaped tail, they can be slightly larger than the average aquarium freshwater fish. The Sword Tail diet consists of commercial fish flakes and vegetables which can be supplemented by live, frosty, or freeze-dried foods.
Sword Tails can live with other freshwater fish in a community tank, but owners should not select bigger tank mates that can eat the Sword Tail. The recommended minimum tank size for the Sword-Tail is 10 gallons.
Swordtail Fish Facts
|Origin||North and Central America|
Platies are perfect freshwater fish for aquarium rookies. They are quite colorful and require minimal care.
Platies can be purchased from pet shops in a wide range of colors. They are livebearers, and will probably eat their young. Although classed as omnivorous, Platies prefer a herbivore diet. They can be fed commercially available fish flakes, and live or frozen food to supplement their diet.
Platies are peaceful fish and can live in a community tank with a minimum tank size of 20 gallons.
Platies Fish Facts
|Size||1.5 – 2.4 inches|
Also known as Lace Gourami, Pearl Gourami is distinguished by its pearlescent body pattern. Pearl Gouramis can be fed commercially available algae-based fish food, and frozen/freeze-dried, or live foods.
A generally peaceful freshwater species, the Pearl Gourami can cohabit with small groups of non-aggressive and similarly-sized tank mates. Pearl Gouramis require fresh surface air to breathe, and the minimum tank size for this freshwater species is 20 gallons.
Pearl Gourami Fish Facts
Although the Kuhli Loach can be easily mistaken for an ell, it is undoubtedly a freshwater fish. A nocturnal creature, the Kuhli Loach is sensitive to abrupt changes in water conditions.
The Kuhli Loach can cohabit with other freshwater fish in a community aquarium, but care should be taken to select fish of similar size to avoid being eaten. The recommended minimum community tank size for this species is 20 gallons.
Kuhli Loach Fish Facts
The Cory catfish is a popular, bottom-dwelling freshwater fish. It is ideal for rookie aquarium keepers, this catfish variety is easy to care for.
Being a bottom-dwelling scavenger, the Cory catfish forages for sinking food pellets and algae particles present in the tank. Cory catfish are peaceful creatures and can cohabit in a community tank with other freshwater fish species. The recommended minimum tank size for this species is 10 gallons.
Corydoras Catfish Fish Facts
The Cherry Barb is a beautiful small fish with colorful horizontal lines across its body. It is a large breeder and females can spawn 200-300 eggs.
The Cherry Barb can be fed a diet of flake food, vegetables, and dried, live, and frozen foods to supplement its protein nutrition. Mature male Cherry Barbs are aggressive, and lots of space is required if they are to cohabit with other freshwater fish in a community tank.
Cherry Barb Fish Facts
This is a peaceful bottom-dwelling freshwater fish. They incline to eat tank plants and must be kept well fed at all times. Tiger plecos can survive on fish pellets and can also forage for sunken food on the bottom of the tank.
Tiger plecos can live in community tanks and can be mildly territorial against other pleco species, so lots of tank space is required if you intend to keep more than one Tiger pleco.
Tiger Pleco Fish Facts
Also known as the Siamese fighting fish, the betta fish is one of the most beautiful freshwater fish species. There are numerous betta variations available to aquarium keepers.
The betta fish can be fed a diet of commercially available fish pellets and freeze-dried or frozen foods. Betta fish males are highly territorial and aggressive and they are best left in solitary tanks.
Female betta fish can cohabit with each other in sorority tanks, or with other freshwater species. The minimum tank size for betta fish is 10 gallons
Betta Fish Facts
Hatchet fish are known for jumping out of their tanks when agitated, and they are not recommended for rookie fish keepers. Hatchet fish can be fed a diet of commercially available live and flake fish foods.
Hatchet fish can be mildly aggressive towards other Hatchet fish, but they can cohabit with other freshwater fish in a community tank. The minimum tank size for Hatchet fish is 10 gallons with a fastened lid.
Glassfish is highly transparent, and a fast-swimming freshwater fish. A Glassfish tank visitor will be struck by its visible skeleton and other internal organs.
Glassfish can be fed a diet of commercially available fresh and frozen fish foods. Glassfish are peaceful and can live in a community tank with a minimum size of 20 gallons, with non-predatory tank mates.
The Discus is a common and big freshwater fish and a type of Cichlids. Discus fish is distinguished by its unique patterns and colors and is vulnerable to changes in their water chemistry.
This fish is recommended for skilled aquarists only. The Discus fish can be fed a diet of commercially available fish pellets, flakes, and live foods. The Discus is a highly social fish and can live with other freshwater fish in a community tank with a minimum tank size of 30 gallons.
|Size||4.8 – 6.5 inches|
Green Spotted Pufferfish
A Pufferfish is a delight to own, but due to its precise care requirements, it is recommended for the highly skilled aquarium keeper.
The Green spotted pufferfish thrives on a carnivore diet of meat, and can be kept in solitary or very large community tanks with other pufferfish only. The recommended minimum tank size is 30 gallons per fish. The tank should also be slightly brackish for the species to thrive.
Green Spotted Pufferfish Facts
The Oscar fish is a cichlid distinguished by its big size, and beautiful colors. This fish is sensitive to water acidity changes, it is recommended only for skilled aquarists.
Oscar fish can be fed a diet of commercially available fresh live foods and vegetables. The Oscar fish is territorial, and can exist in a solitary tank, or can cohabit with similarly large fish in a community tank.
The recommended minimum tank size for Oscar fish is 75 gallons.
Oscar Fish Facts
|Lifespan||10 – 13 years|
Potamotrygon Motoro Stingray
This stingray species is common but expensive and can be kept with a great deal of effort in home aquariums. Stingrays are hard to care for and are recommended only for highly skilled aquarists.
Stingrays are Carnivores and eat live food. They thrive alone or if there is a tank big enough to house them; in groups. The minimum tank size required for this freshwater species is 120 gallons, with a large biological filter fitted.
Potamotrygon Motoro Stingray Facts
|Lifespan||15 – 20 years|