Freshwater aquarium invertebrates

Freshwater invertebrates cover everything that keeps a tank clean or adds movement without being a fish: shrimp in the moss, nerite and mystery snails on the glass, crabs and crayfish over the substrate, and the odd clam in the sand. Each profile lists tank size, water conditions and how the species behaves.

Tank size: 5–53 gal; 5 gal (19 L) to 53 gal (200 L); half the list needs 10 gal (38 L) or more
Temperature: 72–82°F; 22–28°C, most of the list
pH: 6.8–8.0; Most of the list
Difficulty: 46 easy; 51 medium · 6 difficult
Temperament: 62 peaceful; 35 mostly peaceful · 6 aggressive

100 species and 16 varieties

Start here

The freshwater inverts to start with

The Neocaridina shrimp, the cherry shrimp of the shops, is marked beginner at 1.6 inches (4 cm) for 5 gallons (20 liters) and breeds on its own. The Amano shrimp is the algae eater at 2 inches (5 cm). The zebra nerite is the algae snail, marked beginner, and it cannot breed in freshwater. The mystery snail is the pet snail, marked easy at 2 inches (5 cm). The orange dwarf crayfish is 2 inches (5 cm) for 10 gallons (38 liters), marked easy, and the crayfish that leaves plants alone. The Thai micro crab is 1 inch (2.5 cm), fully aquatic, and filters food from the water with feathered claws.

The rule

What every freshwater invertebrate needs

Copper kills all of them at doses a fish never notices, so no copper medication goes in and every fertilizer label gets read. Shells need calcium: snails and crayfish want hard water or a cuttlebone in the tank. Crabs and crayfish climb, up the airline and out of any gap, so the lid is tight. And all of them hate sudden change, so new arrivals are drip acclimated over an hour and water changes stay small.

01
No copper
Medications and some fertilizers kill every animal here
02
Calcium for shells
Snails and crayfish want hard water or cuttlebone
03
A tight lid
Crabs and crayfish climb the airline and out
04
Slow changes
Drip acclimate, change water in small amounts

Shrimp

Shrimp beyond the cherry

The bee shrimp, sold as crystal red and black, wants soft acidic water at a pH from 5.8 to 6.8, 1.2 inches (3 cm) for 5 gallons (20 liters), marked medium. The tiger shrimp is 1.6 inches (4 cm) for cooler water at 64–73°F (18–23°C). The Sulawesi shrimp wants the opposite, 79–88°F (26–31°C) and a pH from 7.5 to 8.5. The bamboo shrimp filters the water with fans at 3.9 inches (10 cm) for 13 gallons (50 liters), and the vampire shrimp does the same at 5.1 inches (13 cm). The ghost shrimp is the cheap one, marked easy.

Snails

Snails beyond the nerite

The gold rabbit snail is 2.8 inches (7 cm) for 16 gallons (60 liters) in warm hard water, and it gives birth to one live baby at a time. The assassin snail hunts other snails at 1 inch (2.5 cm). The red ramshorn and the Malaysian trumpet snail breed to the food supply and tidy leaves and substrate. The black devil snail is a tall, dark snail at 3.9 inches (10 cm) for 13 gallons (50 liters), marked easy. The apple snail reaches 5.9 inches (15 cm), lists 21 gallons (80 liters) and eats plants down to the stem.

Crabs

The purple vampire crab is 1 inch (2.5 cm) for 10 gallons (38 liters), marked medium, and it lives mostly on land, so the tank is a paludarium with more shore than water. The red apple crab and the Thai dwarf rock crab want the same setup. The panther crab is the fully aquatic one, a Sulawesi crab at 4.3 inches (11 cm) for 22 gallons (85 liters) at 75–86°F (24–30°C), and it catches fish. The pom pom crab is fully aquatic and marked easy at 1.6 inches (4 cm) for 5 gallons (20 liters). The Matano crab is another Sulawesi native at 4.3 inches (11 cm) for hard, warm water.

Crayfish and clams

Crayfish and the one freshwater clam

The electric blue crayfish is marked easy and aggressive at 4.7 inches (12 cm) for 20 gallons (75 liters), and it eats plants and any fish it can catch asleep. The Louisiana crayfish is 5.9 inches (15 cm) with the same temper. The marbled crayfish is 3.9 inches (10 cm), marked easy, and clones itself: every one is female and a single crayfish becomes a colony. The Cajun dwarf crayfish is 1.6 inches (4 cm) for 5 gallons (20 liters), marked easy and mostly peaceful. The blue pearl crayfish is a 5.9 inch (15 cm) crayfish marked mostly peaceful for 64–79°F (18–26°C). The Asian gold clam is 2 inches (5 cm), marked difficult, a filter feeder that buries itself and dies unseen.

By the numbers

Smallest

Largest

Easiest to keep

Most peaceful

Fits a 30 gallon tank

FAQ

Common questions

Which freshwater invertebrates are easiest?

The Neocaridina shrimp, the Amano shrimp and the nerite snails are marked beginner. The mystery snail, the assassin snail and the dwarf crayfish are marked easy.

Can shrimp and crayfish live together?

With the dwarf crayfish, mostly, though a slow shrimp gets grabbed now and then. The electric blue, Louisiana and marbled crayfish eat shrimp and get a tank of their own.

Do vampire crabs live underwater?

No. They spend most of their time on land and need a paludarium with a shore, damp moss and a shallow pool. Kept in a full tank they drown.

Do freshwater crabs and crayfish escape?

Yes. They climb the airline, the filter tubing and the corner of the glass. A tight lid with every gap covered is part of the setup.

Do freshwater invertebrates need a heater?

Most list 72–82°F (22–28°C). The Neocaridina shrimp takes 59–84°F (15–29°C), the Sulawesi shrimp and crabs want 79–88°F (26–31°C), and the dwarf crayfish and tiger shrimp run cooler.