Freshwater Invertebrates

While there are not quite as many different invertebrates available in Freshwater aquariums as in Marine aquariums, there are still a wide variety of invertebrates to choose from to add to a Freshwater tank.  Freshwater invertebrates include various snails,  shrimp, crabs, and other crustaceans similar to their saltwater counterparts.

Freshwater Snails

Nerita snails, Japanese Trapdoor snails, Assassin snails, and various other snails  are commonly available to freshwater aquarists.  These are different species than the Asian snails that commonly become a nuisance in freshwater aquariums by hitchhiking on plants.  The snails sold for freshwater aquariums will generally not explosively populate the tank and will actually help keep the populations of nuisance snails down.  Generally they are compatible in most community tanks although some fish such as puffers will eat snails.  They will compete with shrimp and algae eating fish for algae and food.  They are generally affordable and you can keep one every 1-3 gallons of water but at times snails should be given algae wafers to supplement their diet if there is insufficient algae in the tank.

Freshwater Shrimp

Unlike Saltwater shrimp which are typically pricey, many types of Freshwater shrimp are both cheap and readily available.    These include the common Ghost or Glass shrimp, the Grass shrimp, Japanese Amano Shrimp, the Red Cherry shrimp, the Bee Shrimp, the Singapore Flower shrimp, Red Crystal shrimp, and the Mandarin Shrimp.  The Ghost or Glass shrimp will not typically clean algae off of plants like most of the other shrimp will but they are still useful scavengers.  Others like the Japanese Amano or Red Cherry shrimp are great additions to planted aquariums and will keep the vegetation free of algae much like Otocinclus catfish will.  Many like the Ghost or Red Cherry shrimp will commonly reproduce in a home aquarium even without special conditions.  Of course, they will not be compatible with fish that feed on shrimp such as puffers or cichlids.

Freshwater Lobsters

Freshwater “Lobsters” would actually be considered Crayfish by many as the term lobster is usually reserved for saltwater species.  It is purely semantic and in the aquarium trade they are typically called “Freshwater Lobsters.”  Growing up in South Louisiana we called them crawfish and frequently ate large quantities of them at a time!  There are several different species of crayfish “lobsters” available for the freshwater aquarium.  They make an excellent scavenger for ponds or aquariums and will feed upon any leftover food or detritus that settles on the bottom.  They are also algae controllers and will eat any filamentous algae that may form upon the rocks or substrate. However, their diet should also be supplemented with sinking pellet and flake foods that include some algae.

Female lobsters are often more subdued in color and have much smaller claws than their male counterparts. Some species only grow to a maximum size of around 5″ but some can grow up to a foot long.  If kept in outdoor water gardens, many will hibernate during the winter months to survive.

For best care, keep them in an aquarium or pond of at least 20 gallons for the small species and 60 gallons for the larger varieties. They require plenty of rocks for shelter and moderately sized substrate in which it can burrow. They can be aggressive towards other lobsters and require plenty of room for individual territories. Therefore, much larger aquariums or ponds will be needed if housing more than one lobster.

They will not typically bother fish, unless the fish are very small and are slow enough for the lobster to catch. They may also eat plants within the aquarium if sufficient food is not available or they might disturb plants when digging their burrows.

Freshwater Crabs

Surprisingly, there are not really any species of freshwater crabs commonly available for freshwater aquariums that do not require the ability of the crab to get out of the water onto land.  However, there are some crabs commonly available to freshwater aquarists such as the Fiddler crab.

The Fiddler Crab is a hardy species that does well under proper living conditions. The Fiddler Crab originates from the brackish, inter-tidal mud flats, lagoons, and swamps of Florida. As such, the Fiddler Crab requires some salt in the water in order for it to thrive such as a brackish water tank.  The Fiddler Crab is a semi-aquatic species that requires access to an area above the waterline.  A “beach” or “shoreline” made with sandy substrate is ideal. The use of aragonite substrate will help maintain higher pH levels and provide a source of calcium and important trace minerals. The Fiddler Crab aquarium habitat should be aquascaped liberally with rocks, driftwood, and other decorations to offer hiding places and climbing areas. The Fiddler Crab is a capable escape artist so a tight-fitting cover is essential.  The Fiddler Crab is an omnivore that will feed on commercially prepared foods and algae wafers.  There are a few other crabs sometimes found available with similar requirements.

Freshwater Clams

While not as colorful or impressive as their saltwater counterparts, freshwater clams are an interesting and valuable addition to the home freshwater aquarium.  Two species found are the common Freshwater clam and the freshwater Asian Gold clam.

The Freshwater clam is a living filter that helps keep aquarium water clear and clean. By removing uneaten food and detritus from the water column, the Freshwater Clam helps maintain water quality and lower nitrate levels. Like many freshwater bivalves, it typically buries itself in the substrate. However, spotting its siphon protrude from the substrate is truly captivating to observe. The common variety only gets to about 2″, which makes it a suitable addition to well-established aquariums of almost any size.

The Asian Gold clam is another choice for hobbyists seeking the unusual. This ornamental species introduces a delightful golden coloration to the aquarium and the opportunity to observe unusual and entertaining behavior. Unlike many freshwater bivalves, that completely bury themselves in the substrate, the Asian Gold Clam prefers to remain only partially buried.

As a result, the Freshwater Asian Gold Clam is much easier to observe and appreciate. Interestingly, the Freshwater Asian Gold Clam is often quite active at night when you may be able to witness it using its “foot” to lumber across the aquarium bottom.

Freshwater clams should not be housed with large aggressive or carnivorous fish as well as invertebrate-eating fish, such as freshwater puffers.

Freshwater Amphibians

No, they are not invertebrates but the Dwarf African Frog deserves an honorable mention in our website.  The Dwarf African Frog is a true aquatic species and makes a unique addition to the peaceful freshwater community aquarium. However, the Dwarf African Frog is easier to care for and best observed when housed in its very own aquarium. As its name suggests, the Dwarf African Frog is a very diminutive animal that can easily become prey if kept with large fish. This docile frog is slow and meticulous in its movement and feeding behavior. It is not uncommon for faster, more agile fish to consume all the food intended for the Dwarf African Frog. The Dwarf African Frog should be housed in an established aquarium no smaller than 10 gallons in size.  The Dwarf African Frog is a carnivore that requires meaty foods such as frozen or freeze dried bloodworms or shrimp.