7 Best Saltwater Fish For A 30 Gallon Tank

When choosing the right fish for a 30-gallon tank, not only is the amount of water volume important, but the dimensions of the tank is an important factor. 

The standard dimensions of a 30-gallon aquarium are 36” x 18” x 12”. It weighs around 45 pounds empty and 387 pounds when full of water.

I consider any tank under 30 gallons to be a nano-sized tank. So the fish that you decide on keeping need to be suitable for small tanks.

An advantage of having a 30-gallon tank with these dimensions is the 3-foot length.

This sized tank is the largest size for nano tanks so you will be able to keep certain fish that you couldn’t keep in a 10 or 20-gallon tank. 

When choosing fish for a 30-gallon saltwater tank, you need to consider the fish behavior patterns and tankmates as well. 

Of course, a larger tank will be better for the fish, but that is not always possible. 

In this article, I will show you 11 saltwater fish that are perfect for 30-gallon aquariums.

#1. Clownfish


Clownfish are one of the most popular fish in the saltwater aquarium hobby and are a perfect choice for a 30-gallon tank. 

With about 30 different species of clownfish available, you are sure to find the right ones for your tank. The Ocellaris clownfish is a common saltwater fish that are kept in nano tanks.

They will grow to about 3” in size and have a great personality. They are reef safe and won’t bother other tankmates in the aquarium. Unless it’s another clownfish that is.

A pair of clownfish are usually fine together but it’s not a good idea to add another especially in a small tank. 

#2. Bicolor Blenny


This peaceful fish is very easy to care for and is great for beginners. It is also known as the Two-colored blenny.

They will grow to around 4” in size with the males being slightly bigger than females. They have basic coloring with a mix of blue/brown and orange.

The Bicolor blenny is reef safe and usually won’t bother other fish in the tank. This fish needs plenty of live rock to hide in and perch on top of. 

#3. Yellow watchman goby

Watchman Goby

The Yellow Watchman goby is a fish in high demand as so many people love to keep them. They are very unique and fun to watch as they dig in the sand.

These fish are known to form a special bond with Pistol shrimp and they are both beneficial to each other.

They are a very peaceful fish and will only grow to about 4” so they are a great choice for a 30-gallon.

They are also very colorful and will add tons of personality to your nano tank.

#4. Royal Gramma basslet

Royal gramma - (Gramma loreto)

The Royal gramma is a small and slender fish that is a great choice for a 30-gallon tank. It is a colorful fish that has a body with 2 main colors. Purple on the front half and yellow on the other. These fish are peaceful and a great choice for beginners.

They need plenty of live rock and caves to swim around and hide in. The Royal gramma is a carnivore and should be fed a mixed diet of Mysis and brine shrimp, along with other frozen foods.

They will accept flake and pellet foods as well. These fish are all born as females. One member of the group will be the most dominant and turn male.

In a small tank, it is recommended to only have one of these fish.

#5. Bangaii Cardinal

Bangaii Cardinal Fish (Pterapogon kauderni) isolated on white background.
Bangaii Cardinal Fish (Pterapogon kauderni) isolated on white background.

The Bangaii cardinal is one of my favorite fish. They are a very slow-moving and peaceful fish that have a very unique body shape and colors. They are a mix of black and white stripes with dots throughout their body.

These fish stay small and can be kept either in pairs or as a single fish. They will swim throughout all areas of the tank but mostly like to hang out towards the bottom swimming around rocks. These fish are not aggressive and won’t bother other fish in the tank.

They are also reef safe and can be kept with invertebrates. 

The Bangaii Cardinal is an affordable fish. They are available for around $25 at Liveaquaria.com. 

#6. Chalk Bass

Next on the list is a not so common fish but is starting to become a favorite of many tanks. The Chalk bass is a very peaceful fish and an active swimmer. It is a small fish growing to only 3”.

This fish is very colorful with a mix of blue, orange, and purple. It will do great in a 30-gallon tank and is reef safe. They are fun to watch and have a great personality.

If you have a chance to get a Chalk Bass, I recommend that you do. You won’t be disappointed. 

#7. Ruby Red dragonet

Ruby Red Dragonet

Last on the list is the Ruby Red dragonet. This is a very unique and peaceful fish that is reef safe and great for all nano tanks. These are a small fish reaching only 3” in size.

The Ruby Red Dragonet will spend most of its time on the bottom of the tank or on rocks grazing for food. They need plenty of live rock in the tank to graze on. You can keep either a single species or multiple at the same time.

It’s best to keep 2 or 3 females per male in the same tank. Males and females have a noticeable appearance. The male will have a highly developed and retractable dorsal fin.

The biggest concern with keeping these fish is their dietary requirement. They need a healthy population of copepods, amphipods to survive.

Therefore only keep these fish in a mature tank with plenty of food available for them to eat throughout the day.

Read more about these fish here.


If you currently have or plan to set up a 30-gallon saltwater tank, the fish mentioned here are all great options for you. This is not a complete list. There are plenty of fish options available for smaller tanks.

All of the fish mentioned here are generally peaceful fish as smaller tanks are not great options for aggressive fish.

Choosing the right fish for your tank is one of the best ways to ensure success with all saltwater tanks.