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Critters to Keep In Your Tank Aside From Fish: Tank Tips

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While fish usually make up most of the inhabitants in an aquarium, there are other options as well that can actually help your tank! 

If you want to expand your tank and add other critters then look no further!

There are many creatures that can go into a freshwater or saltwater aquarium besides fish! These include snails, shrimp, crabs, clams, starfish, octopuses, frogs and toads, axolotls, and crayfish.

Read on to learn more about each critter you could add to your tank and what you need to do in order for them to thrive! 


Tank TypeSaltwater, Freshwater, and Brackish
Food RequirementsHerbivorous, Omnivorous
Size:0.5 to 4 inches

Snails are great for beginners as they are easy to care for. There are many different options when choosing snails for a tank. 

Most people actually see snails as algae eaters. However, snails cannot live on algae alone. Snails are more beneficial for eating waste and detritus. 

Aquarium snail

They will help by keeping your tank cleaner from all the waste.

Popular saltwater snails:

  • Trochus Snail
  • Mexican Turbo Snail
  • Conch Snail
  • Astrea Snail
  • Nassarius Snail

Popular freshwater snails

  • Nerite Snail
  • Mystery Snail
  • Ramshorn Snail
  • Malaysian Trumpet Snail
  • Assassin Snail
  • Rabbit Snail


Tank TypeSaltwater and Freshwater
Food RequirementsOmnivores and filter feeders
Size1 to 6 inches

Shrimp are always a great addition to any tank. This is because they are considered hard workers as they are constantly cleaning the surfaces inside the tank. 

There are some shrimps that are filter feeders and will constantly be cleaning particles from the water. 

Shrimp are widely available in both freshwater and saltwater tanks. Some even reproduce fairly quickly, meaning a continuous population of shrimps.

Popular freshwater shrimps:

  • Red Cherry Shrimp
  • Amano Shrimp
  • Ghost Shrimp
  • Bamboo Shrimp
  • Pinto Shrimp
  • Tiger Shrimp

Popular Saltwater shrimps:

  • Blood Red Fire Shrimp
  • Banded Coral Shrimp
  • Sexy Shrimp
  • Peppermint Shrimp
  • Scarlet Shunk Cleaner Shrimp
  • Marbled Shrimp
  • Harlequin Shrimp


Tank TypeFreshwater and Saltwater
Food RequirementsOmnivores
Size0.5 to 5 inches

Although there are not a lot of options for crabs in the aquarium market they are a unique addition! 

Some crabs do however require more care than as some are considered semi-terrestrial. 

Crabs are scavengers and some larger ones may be able to eat tank mates that they catch. 

Freshwater crabs tend to be smaller in size, making them perfect for a tank setting. 

Popular freshwater crabs:

  • Fiddler Crab
  • Panther Crab
  • Thai Devil Crab
  • Vampire Crab
  • Red Claw Crab

Popular saltwater crabs:

  • Sally Lightfoot Crab
  • Pom Pom Crab
  • Coral Crab
  • Arrowhead Crab
  • Mithrax Crab
  • Halloween Hermit Crab


Tank TypeFreshwater and Saltwater
Food RequirementsFilter Feeders
Size1 to 48 inches

Most often when clams are thought of people immediately think saltwater. However, there are freshwater clams as well that you can have in an at-home aquarium. 

Not only are they a different kind of pet to have in your aquarium but they also can serve a purpose. 

Clams are called filter feeders. This means they improve the overall quality of water as they remove particles from the water as they feed. 

sThey do have certain needs that need to be met, ensuring proper research is done prior to adding them to a tank.

Popular saltwater clams:

  • Giga Clams
  • Spotted Clams
  • Tridacna Derasa
  • Crocea Clam
  • Tidacna Squamosa

Freshwater Clams:

Freshwater clams are a species within themselves! However, they do go by several commonly known names. 

These include freshwater mussels, basket clams, Asian clams, or Asiatic clams. It is important to note that you should never release freshwater clams back into the wild.


Tank TypeSaltwater
Food RequirementsOmnivores
Size4 to 14 inches

Starfish are the most recognized aquatic species due to their star shape. They are saltwater only and can cause trouble in a community tank. 

Tank mates for a starfish should be chosen carefully to avoid being eaten by the starfish. As an omnivore, the starfish will eat tank mates that are slower.

With many different species of starfish that come in many different sizes, it is very easy to find the right one for you and your tank. Some popular starfish choices are:

  • Indian Sea Star
  • Red Fromia Starfish
  • Brittle Starfish
  • Orange Sea Star
  • Red Serpent Starfish


Tank TypeSaltwater
Food RequirementsCarnivores

Octopus are not only an interesting critter for your tank they are considered to be one of the most rewarding to keep. 

With their intelligence and fascinating behaviors, it is no surprise they are a popular choice besides fish.

Unfortunately, octopuses tend to have a shorter lifespan. They also require more care and need to be fed a certain diet. 

One of the biggest challenges some aquarists have with keeping octopuses is not providing adequate food. 

They need live food such as crabs and shrimp in order to receive their nutrition and enrichment.

Octopuses are very aggressive cutters, only one can be kept in a tank, as they may kill and eat each other. 

This is because the octopus shows no patience for tank mates, as well as having no social instincts. Because of this, there is a very limited list of potential tank mates for octopuses.

Popular saltwater aquarium octopus:

  • Atlantic Pygmy Octopus
  • Common Octopus
  • East Pacific Red Octopus
  • Algae Octopus
  • California Two-Spot Octopus
  • Caribbean Reef Octopos

Frogs and Toads

Tank TypeFreshwater
Food RequirementsCarnivores
Size2 to 2.5 inches

Toads and frogs are typically animals that are seen on land. However, there are a few species that live fully underwater and are available to be kept in aquariums. 

With that being said, some are not able to be placed in a community tank as they will eat the tank mates. 

Also, some species are known for eating the decor in your plant, proper research should be done prior to purchasing.

Popular Frogs:

  • African Dwarf Frog
  • Indonesian Floating Frog
  • Western Clawed Frog
  • Poison Dart Frogs

Popular Toads:

  • Surinam Toad
  • Chinese Fire-Bellied Toad


Tank TypeFreshwater
Food RequirementsCarnivores
Size12 inches

Axolotls are descended from the tiger salamander. Axolotls have just recently had a spike in popularity amongst aquarists. 

However, they are an endangered species and are basically extinct in the wild. They are only captive-bred because of this. Also, they are not legal to keep in all areas.

They are a unique amphibian that lives in their juvenile state throughout their entire lives. They will also be fully aquatic during their entire life. 

They should not be kept with other animals and have certain care requirements.

Although they require more complex care requirements they can live up to 10 years. For example, they can become stressed from not having their temperature needs met. 

This stress makes them more likely to develop many different illnesses and infections.


Tank TypeFreshwater
Food RequirementsOmnivores
Size2 to 8 inches

Crayfish are invertebrates that are similar looking to shrimp. Although they have poor temperaments that make it very difficult to place them into a community tank. 

As they will eat anything that they are able to catch. Thankfully most move slowly, lowering the risk of them eating tank mates. 

However, there are some that are dwarf crayfish that fare better in community tanks as they are very small.

Popular freshwater crayfish

  • Dwarf Orange Crayfish
  • Australian Red Claw Crayfish
  • Dwarf Blue Crayfish
  • Red Swamp Crayfish
  • Common Yabby
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