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6 Small Saltwater Aquarium Fish

If you’re interested in setting up a marine aquarium but don’t have much space available, you might be wondering if you have any options when it comes to stocking your tank. After all, many fish grow quite large and need a lot of space to thrive.

Fear not! In this article, we’ll discuss 6 small saltwater fish that you can keep in an aquarium of 30 gallons or under.

Infographic Showing 6 Small Saltwater Aquarium Fish

Ocellaris clownfish (Amphiprion ocellaris)

The ubiquitous ocellaris clownfish was a staple in the reef hobby even before Finding Nemo came out. It’s really the ideal small saltwater aquarium fish: colorful, peaceful, reef safe, easy to keep and very active. Need we go on?

Because this species only grows to about 4.3” in length, you can keep them in a single-species set-up as small as 20 gallons. Be sure to go for a pair! Although ocellaris clownfish can be kept alone, they’re much more fun to watch when they’ve got a partner.

You can learn more about this species in the full ocellaris clownfish care guide.

Did you know? Having an anemone is not a must for your clownfish. A torch coral is easier to grow and generally works just as well.

Ocellaris clownfish, a small saltwater aquarium fish, underwater photo in anemone.

Lawnmower blenny (Salarias fasciatus)

The comical lawnmower blenny is not just appreciated for its wacky looks (would you look at that face?!) but also for its efficient gardening capacities. The species’ common name is derived from the fact that they have a taste for algae and can therefore help you keep your aquarium clean and neat.

Because the lawnmower blenny is a bottom dweller that doesn’t need loads of space to move around, combined with its maximum length of around 5”, you can keep one in an aquarium of 30 gallons or up.

You can find out more in the full lawnmower blenny care guide.

Six line wrasse (Pseudocheilinus hexataenia)

There are many beautiful wrasses available in the aquarium hobby and the colorful six line wrasse is no exception in this. Its neon orange and dark blue striped pattern is sure to catch the eye! One other good thing about this species is that it stays smaller than many other wrasses. At a maximum size of around 4”, it’s suitable for an aquarium of at least 30 gallons.

Keep in mind that the six line wrasse is reef safe but doesn’t always play nice with its fishy neighbors. You might want to make it the last species you introduce into your tank, just to ensure the other inhabitants have already established their own territories.

You can find out more in the full six line wrasse care guide.

Firefish goby (Nemateleotris magnifica)

The smallest species on this list, the tiny firefish goby rarely reaches a length of more than 3”. This means you can keep a single firefish goby, or a mated pair, in a set-up as small as 20 gallons.

Firefish gobies are naturally plankton eaters but they have no issues accepting frozen foods in the aquarium. The species is docile, reef safe and peaceful except when it comes to other gobies.

You can find out more in the full firefish goby care guide.

Firefish goby (Nemateleotris magnifica) underwayer photo, a small saltwater aquarium fish

Yellow watchman goby (Cryptocentrus cinctus)

Like the lawnmower blenny, which we previously discussed, the yellow watchman goby is a small bottom dweller. They grow to only 4” in length and tend to stay in or near their burrow, meaning they don’t need too much space. An aquarium of 20 gallons or up is enough to maintain a single yellow watchman goby.

If you want to see the goby’s natural behavior, you could consider pairing it with a pistol shrimp. The two species naturally maintain a symbiotic relationship in which the shrimp maintains the pair’s burrow, while the goby provides protection and food scraps.

You can find out more in the full yellow watchman goby care guide.

Yellow watchman goby (Cryptocentrus cinctus)

Blue green chromis (Chromis viridis)

The immensely popular blue-green chromis is a big favorite among saltwater aquarists. The stand-out colors, peaceful nature, small size and easy care of this small saltwater aquarium fish just make it an all-around great choice for beginners and more experienced aquarium enthusiasts alike.

The blue green chromis is a shoaling fish, meaning it’ll appreciate a group size of at least three. Combine this with a maximum size of around 4” in length and you don’t need much more than a 30 gallon aquarium to keep this species.

Blue green chromis (Chromis viridis), a small saltwater aquarium fish


A well-maintained marine aquarium is a joy to see, but choosing the right fish and keeping things in order is not always easy. If you feel you lack the time or knowledge to care for the small saltwater aquarium fish mentioned here, we can help! FantaSEA Aquariums designs, builds and maintains custom aquariums. Contact us here with your ideas!

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Marijke Puts

Hey! I'm Marijke, FantaSEA's resident blog writer. I'm a full-time pop science author, part-time PADI diver and snorkeler, and have been keeping fish since I was a kid. When I'm not writing fish care guides, you can usually find me underwater or trying to figure out how to fit more tanks into my house.

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