Pet Ideas for 5- and 10-Gallon Aquarium Tanks

Looking for the Best Pets for a 5- or 10-Gallon Tank?

So you’ve just pulled out a dusty old aquarium from the basement and are now wondering if there are any interesting animals you can keep in it to avoid throwing it away or pursuing an arduous search for someone who’d be willing to come pick it up from your house (shipping them would be far more expensive than the unit itself). You can consider a limited number of animal species that can reside in your tank for their entire lives, livening up a boring room space with movement, and/or a natural, thriving aquatic or terrestrial ecosystem.

First things first:

  • Make sure you clean out your aquarium with vinegar only. Never use any chemicals or soap.
  • Research is paramount to finding a pet that best meets the level of commitment you’re willing to put into them, as well as one that doesn’t tax your pocketbook.
  • Never place any animals in an aquarium unsuited for their adult size while they are neonates, unless you are prepared to switch them later. Viewing animals thriving and behaving in a properly sized environment is very rewarding.

Pets for a 5-Gallon Tank

Generally, only experienced keepers will push the envelope but it is always best to do everything in your power to assure a comfortable existence for your pet. For most animals, bigger is better, and with small tanks comes more maintenance to compensate for excess nutrient levels (animal waste turning into nitrates). Think in terms of long term success for best results, don’t purchase any pets that you don’t foresee living at least five years in your five gallon tank.

Observe the behavior of prospective fish for your tank before buying them. Do they utilize a lot of horizontal swimming space? Do they tend to stay toward the bottom? Ignore the ‘1 inch per gallon’ rule as it is meant to be utilized with a minimum tank size in mind. Many retailers advertise with photos of five gallon tanks with everything in them from angelfish to lizards, but it is by no means acceptable to house a majority of these species in this amount of space. Always do careful research to pick fish for small tanks to insure they are suitable, and to find out if they should be kept alone, or with tank-mates.

With that said, what are some of these suitable creatures?

African dwarf frogs are an excellent choice for five gallon tanks, and are probably the most suitably-sized vertebrate for nano aquariums. These tiny frogs are not to be confused with African clawed frogs, a much larger species.

Also, fire belly toads are a small frog species that can minimally tolerate a 5 gallon tank size, but again, this is not ideal and many keepers would recommend against it.

3. Marine Fish

There is some controversy on what fish are suitable for a five gallon tank. Even relatively large fish like the smaller clownfish species are routinely kept in what are referred to as nano-reefs. Unless they are babies, I wouldn’t recommend clownfish. My preferred recommendation for a five gallon is to stick to the invertebrates listed above.

However, for those determined to have fish inhabitants, here are a few species that some people keep in smaller tanks because they are ‘perching’ fish as opposed to swimmers, although it is not considered to be ideal:

  • Neon goby
  • Clown goby
  • Trimma Goby
  • Eviota Gobie
  • Catalina Goby (needs colder water)

As mentioned already but it bears repeating: invertebrates would do very well in a five gallon.

The popular flame scallops fare very poorly in captivity.

4. Dwarf Seahorses

Dwarf seahorses are another option for your five gallon tank. However keep in mind, while they may sound like an exciting animal to consider because they are the right size and very slow swimmers, they still require very particular care. In fact, dwarf seahorses require small tanks in order to feed. However, they are not very easy to care for, and require live brine cultures for their food. For the more adventurous aquarist however, this is one option that will dazzle a small tank.

5. Other Invertebrates

There are many other invertebrates that you can consider for your aquarium, like land arthropods. For those into animals that most would consider ‘creepy’, many pet bugs are suitable for five gallons:

  • Tarantulas
  • Tropical Cockroaches
  • Millipedes
  • Scorpion

Remember that all tarantulas, centipedes, and scorpions are venomous. Also, some species are larger and not recommended.

Pets for a 10-Gallon Tank

Ten-gallon aquariums are some of the most popular tanks on the market. Nearly all pet lovers have a spare one floating around somewhere. Despite not being drastically larger than a five gallon, you have a little more leeway stocking-wise with the few extra inches of horizontal space that a 10-gallon offers. Ten-gallons are the minimal size for many species, and unlike the five gallon, you can also keep a few snakes in this size. For most species of the species mentioned here however, upgrading to a 20-gallon is considered to be more optimal. However, the following are still appropriate and can be housed in a 10-gallon tank.

1. Freshwater Fish and Invertebrates

Many species of freshwater fish are said to do well in larger tanks, and this is a standard size for beginners. Fish species include (aside from those already listed for the five gallon) but are definitely not limited to:

  • Groups of tetras
  • Pygmy cory
  • Pygmy hatchetfish
  • Gouramis
  • Norman’s Lampeye
  • Butterflyfish

2. Snakes

While most snakes do not need tanks longer than the size of their bodies, they should still have some room to roam around. It is not uncommon to see popular beginner snakes like corn, king, and milk snakes kept in 10-gallon aquariums as adults, but this is a little on the small side, especially if a particular snake grows larger than expected. However there are some snakes that are small enough to reside comfortably in a to gallon for their whole lives. These include:

  • Scarlet king snake (if you can find one)
  • Kenyan sand boa
  • Egg-eating snake (Dasypeltis species)
  • Smaller garter snakes
  • Rosy boa
  • Western and Eastern hognose
  • Also some other species if they remain small after reaching adulthood. Perhaps consider adoption/re-homed snakes that have reached adult age (at least three years)

The snakes, as do all pets, listed all require research into their care. Egg-eating snakes for example, must be large enough to handle quail eggs or they will require hard to find finch eggs from bird breeders. They may also need supplemental biotin.

3. Lizards

Lizards can be suitable for 10 gallon tanks. However 10 gallons is about the minimum tank size that can be done with even the smallest lizards. Lizards tend to be active and nocturnal. Geckos are the most popular choice for smaller lizards.

  • Geckos: Leopard geckos, African fat tailed geckos, house gecko, panther geckos, crested geckos, golden geckos, flying geckos, day geckos
  • Anole species
  • Pygmy chameleons

4. Frogs and Amphibians

Frogs and amphibians are popular options for this size. You can consider from the following, among others:

  • Fire belly toad
  • Pacman frog
  • Reed frog
  • American green frog
  • Some small newts can fit, but with the filtration they require, a bigger tank might be needed
  • One axolotl (some non-academic hobbyists recommend a minimum of 20 gallons, and while as a general rule, bigger is better, there is no evidence 10 gallons is inadequate as long as the water quality is maintained.) [1-8].
  • African clawed frog

Note: Poison dart frogs are very small, but are generally recommended to have at least 20 gallons.

5. Hermit Crabs

Aside from the other arthropods listed for the five gallon tank, hermit crabs are popular starter pets often kept in 10-gallon aquariums. However, there is much misinformation about them being spread by pet stores that are in the business to make sales and this leads to a high mortality rate in captivity. As far as hermit crab care is concerned, be sure to provide hermit crabs with at least six inches of sand or coconut fiber for burrowing, access to salt water, climbing branches, hiding places, and proper humidity levels. Hermit crabs should also be housed with at least two individuals as they are social animals.

A crayfish tank is another option.

6. Marine or Saltwater Fish and Invertebrates

There are plenty of options for saltwater tanks for 10-gallon aquariums, starting with corals which can be kept in tanks as small as 0.5 gallons. A reef-only tank with ‘cleaner crew’ invertebrates are highly recommended because the lack of fish will make the water quality easier to maintain, and the extra space a 10-gallon offers could really allow for some amazing aquascaping. For those who are fixed on adding fish, opinion varies for different species, but the following are safe bets:

  • Clownfish (most species except the maroon clown which gets rather large)
  • Yellow watchman goby
  • Firefish
  • Small wrasses

There are certainly other small fish that would be recommended by many. A Randall’s pistol shrimp and yasha hase goby pair demonstrate the interesting phenomenon of a symbiotic relationship between two different species and would be very comfortable in a 10-gallon.

However make sure you avoid the beautiful but not easy to care for scooter blennies and mandarin dragonet fish, which require large mature tanks in order to feed.

7. Species-Only Tanks

For those interested in something more unusual for their 10-gallon, consider species tanks or species-only tanks.

An aquarium can be dedicated to animals like:

  • Tube anemones
  • Nudibranchs
  • A planted saltwater tank
  • Cherry-picked zoanthids

The tanks can be dedicated to these species only:

  • Mantis shrimp (no other inhabitants)
  • Harlequin shrimp (feeds exclusively on starfish)
  • Small frogfish (will eat other fish and invertebrates)