7 Unique Invertebrates for Your Aquarium: Quirky and Fun

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When it comes to stocking your aquarium, fish often steal the spotlight, and there are certainly some beautiful species to choose from. However, a whole world of fascinating invertebrates is also waiting to be discovered, so you don’t have to limit your aquatic pet choices to fish!

From quirky shrimp to amazing, mesmerizing cephalopods, these creatures can add an exciting and unique element to your tank. And these amazing animals aren’t limited to marine and reef tanks; there are freshwater species, too.

Here are seven unusual invertebrates you might like to consider for both freshwater and saltwater aquariums.

Key Takeaways

  • Invertebrates like Vampire shrimp and Thai Micro crabs make excellent freshwater pets due to their peaceful nature, interesting feeding behaviors, and tank-cleaning abilities, suitable for community aquariums of 20 gallons or more.
  • Saltwater invertebrates, such as Peacock Mantis shrimp and Harlequin shrimp, offer eye-catching visuals and unique behaviors but require species-specific tanks and careful attention to dietary needs, starting at 20 gallons.
  • Highly specialized and visually stunning pets like the Blue Ring octopus and Flamboyant cuttlefish are recommended for experienced aquarists. Due to their complex care requirements, these creatures require a minimum of 30-gallon aquarium and a species-only tank setup.

Summary Table

Here’s a quick, at-a-glance summary of the critters we’ve included in this article! Do bear in mind that some of these aquatic animals have complex care requirements, so be sure to research your chosen species thoroughly before taking it on.

Common Name Scientific Name Ideal Water Parameters Origins Diet Size Lifespan Minimum Tank Size Average Cost
Vampire Shrimp Atyopsis moluccensis pH: 6.5-7.5, Temp: 72-82°F Southeast Asia Algae, detritus, sinking pellets Up to 3 inches 2-3 years 20 gallons $10-$20
Thai Micro Crab Limnopilos naiyanetri pH: 6.5-7.5, Temp: 72-82°F Thailand Algae, detritus, leftover food Up to 0.8 inch 1-2 years 5 gallons $5-$10
Freshwater Pom Pom Crab Ptychognathus barbatus pH: 6.5-7.5, Temp: 72-82°F Southeast Asia Algae, detritus, sinking pellets Up to 2 inches 2-3 years 10 gallons $10-$20
Peacock Mantis Shrimp Odontodactylus scyllarus pH: 8.1-8.4, Temp: 75-82°F Indo-Pacific Fish, crustaceans, mollusks Up to 7 inches 3-5 years 30 gallons $20-$50
Harlequin Shrimp Hymenocera elegans pH: 8.1-8.4, Temp: 75-82°F Indo-Pacific Starfish Up to 2 inches 1-2 years 20 gallons $30-$50
Blue Ring Octopus Hapalochlaena sp. pH: 8.1-8.4, Temp: 75-82°F Indo-Pacific Small fish, shrimp, crabs Up to 5 inches 6-12 months 30 gallons $50-$100
Flamboyant Cuttlefish Metasepia pfefferi pH: 8.1-8.4, Temp: 75-82°F Indo-Pacific Shrimp, fish, crustaceans Up to 3 inches 1-2 years 30 gallons $50-$100

Freshwater Options

First of all, let’s take a look at some of the most interesting, quirky freshwater creatures you might fancy keeping as pets.

Vampire Shrimp (Atyopsis moluccensis)

Atyopsis moluccensis

If you’re an experienced aquarium owner looking for an interesting addition to your tank, you might want to consider taking on Vampire Shrimp.

These fascinating creatures are native to the tropical waters of Southeast Asia. These strange little shrimp are great fun to watch as they position themselves on vantage points around the aquarium, using their feathery appendages to filter tiny particles of food from the water.

Vampire shrimp are peaceful creatures that spend most of their time perched on driftwood or rocks, making them a great addition to a community tank with other peaceful fish that won’t bother them. As mentioned above, these shrimp are filter feeders but will also eat sinking pellets and algae wafers. If you’re planning to keep these shrimp, you’ll need a minimum tank size of 20 gallons.

Vampire shrimp are not only interesting to watch, but their unique appearance and peaceful nature make them an excellent addition to any aquarium.

Thai Microcrab (Limnopilos naiyanetri)

Thai Microcrabs can make a cute, unique addition to any densely planted aquarium.

Despite their diminutive size, these fascinating crabs are extremely active and highly entertaining to watch, spending much of their time scavenging for food and climbing on plants and your aquarium decorations. They are omnivorous and will happily eat algae, detritus, and leftover fish food, making them great for keeping the tank clean and tidy.

Thai microcrabs are benign creatures and can be kept with other peaceful fish and shrimp species, and with a minimum tank size requirement of just 5 gallons, they are perfect for nano tanks. Their quirky behavior and small size make Thai Microcrabs a popular choice for aquarists looking to add an unusual element to their aquarium.

Freshwater Pom-Pom Crab (Ptychognathus barbatus)

Freshwater pom-pom crabs are unique, fascinating creatures that can add an interesting dimension to any freshwater aquarium.

These crabs are native to Southeast Asia and are best known for their oversized claws, which are covered in small hairs resembling pom-poms. Pom-pom crabs are relatively peaceful but can be territorial, so keeping them with peaceful fish and shrimp species is important.

Freshwater pom-pom crabs are omnivorous and will eat algae, detritus, and sinking pellets, making them an excellent addition to any aquarium cleanup crew. With a minimum tank size requirement of only 10 gallons, these crabs are also suitable for nano tanks.

Their quirky appearance and interesting behavior will make Pom-pom crabs an eye-catching addition to your freshwater tank. In addition, these creatures are relatively low maintenance and are sure to grab the attention of anyone admiring your aquarium.

If you’re looking for a unique and unusual aquatic pet, a freshwater pom-pom crab might just be the perfect addition to your freshwater tank.

Saltwater Aquarium Options

If you have a reef or marine aquarium of a decent size, you have a good selection of invertebrates to choose from. However, some of these critters have quite complex care needs and are best suited to experienced aquarists.

Peacock Mantis Shrimp (Odontodactylus scyllarus)

Peacock Mantis Shrimp (Odontodactylus scyllarus)

Peacock mantis shrimp are amazing creatures that are found in the Indo-Pacific region. They are known for their powerful claws, which they use to crack open the shells of their prey.

These shrimp are highly intelligent creatures with excellent eyesight, making them skilled hunters. Although they might not be suitable for life in community tanks, peacock mantis shrimp are extremely interesting to watch. Their brightly colored appearance and unique behavior make them a truly captivating addition to a marine aquarium.

Peacock Mantis shrimp are carnivorous, feeding on a variety of meaty foods, such as fish, crustaceans, and mollusks. For that reason, you should keep your shrimp in a species-only tank, as they are aggressive and can harm other tankmates.

If you plan on keeping peacock mantis shrimp, you’ll need a minimum aquarium size of 30 gallons.

Harlequin Shrimp (Hymenocera elegans)

Harlequin Shrimp (Hymenocera elegans)

Harlequin shrimp are an exquisite addition to any aquarium due to their unique feeding habits and striking appearance.

Originating from the Indo-Pacific, these shrimp have specialized claws that they use to flip over and consume the tube feet of starfish, making them obligate starfish eaters. Due to their specific dietary requirements, Harlequin shrimp are best kept in a species-only tank or with peaceful tankmates who won’t be viewed as food.

Harlequin shrimp are relatively low maintenance once their dietary needs are satisfied, and their minimum tank size requirement is just 20 gallons. These shrimp are visually stunning, and their feeding behavior is fascinating to watch, making them an excellent choice for experienced aquarists looking for a unique addition to their marine aquarium.

Blue Ring Octopus (Hapalochlaena sp.)

Blue Ring Octopus (Hapalochlaena sp.)

Before introducing our next enchanting sea creature, a word of warning. Blue Ring octopuses are highly venomous and should only be kept by experienced aquarists.

These enigmatic creatures are native to the Indo-Pacific regions and spend much of the day hiding in caves or crevices, only becoming active at night. Because of their venomous qualities and aggressive nature, Blue Ring octopuses should be kept in a species-only tank.

These creatures are carnivorous and will eat a variety of meaty foods, including small fish, shrimp, and crabs. If you’re an experienced aquarist looking for an intriguing, unique addition to your saltwater tank, a blue ring octopus might be just what you’re looking for.

These highly intelligent creatures have captivating behaviors that make them a joy to watch, but a 30-gallon, single-species tank is essential to keep them healthy and happy.

Flamboyant Cuttlefish (Metasepia pfefferi)

Flamboyant Cuttlefish (Metasepia pfefferi)

The Flamboyant cuttlefish certainly lives up to its common name, and if you’re looking for a visually stunning and fascinating invertebrate to add to your aquarium, this creature is an excellent choice.

These cuttlefish are found across the Indo-Pacific regions and are well-known for their amazing, vibrant colors and unique swimming style. What’s even more impressive is their ability to change color and texture to blend in with their surroundings, making them incredibly interesting to observe in your aquarium.

However, it’s important to note that Flamboyant cuttlefish must have a species-only tank or a few peaceful tankmates that won’t harm them. These glamorous critters are carnivorous and will eat a variety of meaty foods, including shrimp, fish, and crustaceans, which is another reason a species-only tank is a good option for these guys.

As with many of the invertebrates we’ve featured in this guide, the Flamboyant cuttlefish has specific dietary needs, so it’s essential to research their requirements before taking them on.

In terms of tank size, a minimum of 30 gallons is recommended for these creatures. Once their needs are met, the Flamboyant cuttlefish is relatively low maintenance and can make a great addition to your aquarium. Their unique behavior and stunning appearance are sure to captivate the attention of any onlooker.

If you’re an experienced marine hobbyist looking for a unique and visually striking invertebrate to add to your collection, the Flamboyant cuttlefish is definitely worth considering.

Final Thoughts

Whether you have a freshwater or saltwater tank, introducing a few of the unique inverts we’ve featured in this guide can provide endless fascination for you and your visitors!

However, many of these weird and wonderful creatures have very specific care requirements, so please remember to research each species carefully to ensure they are compatible with your aquarium environment and you can meet their specific needs for a long, happy, and healthy life.

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