Best Saltwater Fish For a 30 Gallon Tank

If you have recently acquired, or are planning on owning a 30 gallon saltwater fish tank it makes sense to figure out what fish you can house in it, and certainly, which are the best fish to keep in it. 30 gallons is a good size tank and you will have plenty of good options that range in size and colors.

Here is a shortlist of our top 5 best saltwater fish for a 30 gallon tank:

  • Royal Dottyback
  • Green Mandarin Dragonet
  • Flame Angelfish
  • Pajama Cardinal
  • Purple Firefish Goby

We have detailed summaries and requirements for each of these fish as they relate to your 30 gallon tank.

There are two types of fish you will likely introduce to your 30 gallon saltwater fish tank; aggressive and non-aggressive fish. Now, you may think that it is a no-brainer to choose the less aggressive fish due to their compatibility with other marine life, but you might be surprised that this is not the only choice.

30 gallon saltwater fish tank

Some of the most beautiful and majestic fish are equally some of the most aggressive and incompatible. On the flip side, there are many beautiful non-aggressive fish that will not terrorize your saltwater aquarium and allow you to house many other fish species.

30 Gallon Saltwater Fish (List)

Owning a saltwater fish tank of any size comes with a tremendous amount of responsibility, especially with a 30 gallon tank as you will likely house multiple fish from different species together, which is not typically the case with a 10 gallon saltwater fish tank. So, choosing those that are compatible is paramount, as well as those that will actually thrive in a tank of this size and will not find it too small or too big to live comfortably in. Without further ado, let's dive in!

1. Royal Dottyback

The beautiful and elusive Royal Dottyback (Pictichromis paccagnella) is certainly one of, if not the most attractive fish to feature on this list. The only real drawback is their semi-aggressive tendencies. Their abundantly bright half yellow and half purple body certainly makes them stand out, and this unusual coloration suits their outgoing and confident personality excellently. Royal Dottybacks are hardy little fish, making them perfect for beginner hobbyists, but they do get territorial, so, watch out for that.

Royal dottyback

Typically, they will only become aggressive with other fish if they are the same size and members of their own species. The key to having more than one of these Dottybacks residing in your tank without problems is by introducing them at the exact same time so that they can establish hiding spots within your 30 gallon saltwater fish tank. Their minimum recommended tank size is a 20 gallon saltwater fish tank, but the bigger the better and it is less likely you will experience problems with territories if you have a bigger tank.

2. Green Mandarin Dragonet

Green Mandarin Dragonets are a type of saltwater fish that are in a league of their own when it comes to their unique appearance and sensational coloration. Additionally, they are affordable too, which is often not the case when it comes to such rare fish. Their vibrant colors are mesmerizing, sporting a deep-green body as the primary color, which is covered in blue and orange lines that freely flow around the entire body, not following a specific straight pattern.

Mandarin Dragonet

Fortunately, they are also very peaceful reef-safe fish, which makes them a fantastic option for a 30 gallon fish tank. The only real showcase of aggression that is displayed by these fish is towards other males of the same species, so, make sure you do not keep 2 mandarin dragonet males in the same tank!

Their tank requirements are a little more specific than most of the other fish featured on this list. Firstly, make sure you do not add them to a brand-new aquarium, they need an established aquarium in order to feed off amphipods and copepods that appear in established environments.

Secondly, they need to live in a 30 gallon tank or larger, and the tank must contain a lot of live rock and live sand substrate for them to hide and play in.

3. Flame Angelfish

Flame Angelfish are certainly one of the most popular saltwater fish in the hobby. This is due to their vibrant coloration, sporting a deep red/orange body, paired with vertical black stripes and neon blue fin accents. Additionally, these beauties are beginner-friendly and a joy to care for. The only real issue with these angels is that they have been known to nip at corals, resulting in a damaged reef, so, be careful.

Flame Angelfish

Flame angels ideally need to be in an aquarium no smaller than 30 gallons. When in small aquariums they can become aggressive towards other fish, especially if they are not being fed enough. 30 gallons is perfect for keeping one flame angel and perhaps some invertebrates too, but if you want more than one, go for a tank larger than 30 gallons.

4. Pajama Cardinal

These awesome fish are not only peaceful, but they are also schooling fish, meaning that you can keep a few in your 30 gallon saltwater fish tank without any problems.

Their pattern and coloration are truly unique and eye-catching too, showcasing silver bodies with red and orange dots, amusingly resembling polka dot pajamas! Their eyes are large and red, however, despite the menacing look, they are incredibly friendly, playing well with others.

Pajama Cardinalfish

The Pajama Cardinal is very hardy, as well as being brilliant for beginners since they are easy to care for and do not have complicated dietary requirements.

Due to their schooling nature, it is strongly advised to keep a minimum of three Pajama Cardinals or more in your fish tank at a time. Make sure to populate your 30 gallon tank with lots of hiding spots for these guys, as they love hiding and playing,

5. Purple Firefish Goby

These gorgeous little gobies will make for an awesome addition to a 30 gallon saltwater tank. They are easy to manage and adapt very well to small aquariums, not to mention, they get along well with most other saltwater fish of a similar size and temperament, so, finding purple firefish goby tank mates shouldn't be an issue.

Given away by their name, these gobies showcase a white body and vibrant purple fins with orange accents, looking sensational in any reef environment. They have a very passive and peaceful nature, getting along very well with similar-sized tank mates.

Purple firefish

Like some of the other fish on this list, these gobies can become aggressive towards their own kind, so it is advised to keep them singularly, or as a mated pair. Something to bear in mind is that these energetic little fish are brilliant jumpers, so ensuring your tank's lid is properly secured is of the utmost importance.


Here are our answers to some frequently asked questions by hobbyists.

How Many Saltwater fish Can I Put in a 30 Gallon Tank?

There are no specific number of fish attached to the capacity of a 30 gallon tank, instead, you should use the rule of "1 inch per gallon". So, if you work out that the fish you would like to add are 3 inches in length (when they are fully grown), you should add no more than 10 to your 30 gallon saltwater aquarium.

How many clownfish can I put in a 30 gallon tank?

This is a good question and it depends on the size of the clownfish you are planning on adding to your 30 gallon tank. The most commonly purchased clownfish species by hobbyists is Ocellaris Clownfish (Amphiprion Ocellaris), which typically grow to 3.0-3.5 inches in length. Based on the 1 inch per gallon rule you can add about 8-10 of these clownfish, but make sure that you have one dominant female and the rest male for the group to work in harmony.


There are many fantastic fish out there that are perfect for 30 gallon saltwater fish tanks. However, the fish that feature on our list not only possess very compatible personalities, but they are truly beautiful too, displaying enough unique patterns and colorations that some of them even feature on our most colorful saltwater fish list!