What are the Different Types of Freshwater Species?

A diverse range of fish, reptiles, and amphibians make up the world's freshwater species. Though the majority of the thousands of animal species found in freshwater sources are fish, many amphibian and reptile species also make up the freshwater community. Several mammal, bird, and insect species can also be found living fully or partially in freshwater.

Fishermen may be familiar with the vast array of fish species found in freshwater sources. Dozens of species of corydoras and catfish thrive in these communities. Many different types of pleco fish also live in freshwater. Suckermouth fish, from larger catfish varieties to the dwarf versions captured for aquarium use, live in rivers and streams.

Many different types of squeaker, hatchetfish, and syno fish can be found in freshwater. The popular tetra fish that people enjoy keeping as pets are freshwater fish. Some shark species, such as the bull shark, can live in freshwater. They usually return to saltwater, however, to breed. Certain river sharks, found mostly in Asia and Australia, can fully live and breed in freshwater. The Speartooth shark and Irrawaddy River Shark are two examples.

Like freshwater fish, many reptile and amphibian freshwater species are often caught to be kept as pets. Turtles, such as the red-eared slider, are commonly discovered and kept as such. Some endangered species, such as the striped legless lizard, also live in freshwaters. Frogs, such as the African dwarf and clawed varieties, often make their homes in ponds, streams, and other inland waters. Salamanders and newts, also popular pet choices, typically live in these habitats as well.

Several freshwater species of insects provide food for many of the other freshwater animals. Many of these species, such as the common fly, dragon fly, and mosquito, make their homes in freshwater areas. Water striders and spiders can also be found in these habitats. Many other invertebrates, such as worms and leeches, are also freshwater species.

Most mammals do not live fully immersed within water. The dolphin and manatee, however, are two mammalian species that can live fully in fresh water. Marshes are home to many mammal species, including the muskrat and nutria. Beavers, otters, and platypuses, also mammals, spend much of their time in freshwater as well.

Freshwater bird species often hail from marshy areas. The crane is one of the most well-known freshwater birds. Other avian freshwater species include egrets, herons, woodpeckers, and some types of eagles and hawks.

Freshwater species are typically categorized into three main groups: vertebrates, invertebrates, and plants. Vertebrates include fish, amphibians, reptiles, birds, and mammals that are adapted to live in freshwater environments. Invertebrates encompass a wide range of organisms such as insects, mollusks, and crustaceans. Freshwater plants can be either fully submerged, floating, or emergent, depending on their adaptation to aquatic life.

According to the Food and Agriculture Organization of the United Nations, there are over 18,000 known species of freshwater fish globally. This diversity represents more than 40% of all fish species, highlighting the richness of freshwater ecosystems. These species play crucial roles in their habitats, from being key predators to serving as food sources for other wildlife and humans.

Freshwater invertebrates include a vast array of species such as dragonflies, mayflies, and caddisflies, which often start their life cycle in water before becoming airborne. Aquatic worms, snails, and freshwater mussels are also common, with mussels playing a significant role in filtering and purifying water. Crayfish and freshwater shrimp are other examples, contributing to the ecosystem as both prey and predator.

Yes, several mammal species are adapted to freshwater ecosystems. For instance, the North American beaver is known for its dam-building activities that can alter landscapes. Otters, which are found on multiple continents, are adept swimmers that hunt in water. The Amazon river dolphin, a freshwater cetacean, is a remarkable example of mammalian adaptation to riverine environments.

Freshwater plants are essential for maintaining healthy aquatic ecosystems. They produce oxygen through photosynthesis, provide habitat and breeding grounds for fish and invertebrates, and stabilize sediments. Plants like water lilies and duckweed offer surface cover, reducing algae growth by limiting sunlight penetration. Submerged plants, such as eelgrass, are vital for oxygenating water and serving as food for various species.

Unfortunately, freshwater species are facing significant threats, with habitat loss, pollution, overfishing, and climate change being major contributors to their decline. The International Union for Conservation of Nature (IUCN) has reported that freshwater species are declining at a faster rate than terrestrial or marine species, with some populations experiencing severe reductions, making conservation efforts critical for their survival.