Semi Aggressive Saltwater Fish

Having a saltwater aquarium with some of your favorite fish is a great idea. Except when your favorite fish becomes aggressive and starts to bully others in the tank. An aggressive or semi-aggressive saltwater fish can become a huge pain not only for other tankmates but for you as well.

Fish are generally classified as peaceful, semi-aggressive, or aggressive. Predatory saltwater fish will normally only get along with others of the same species. Many people own predator tanks and they are pretty impressive but definitely not for beginners. Peaceful saltwater tanks will generally have fish like the Blue/Green Chromis and Clownfish.

These tanks are non-aggressive and you won’t have to worry about losing money on expensive fish due to territorial issues and bullying. But if you are looking to introduce a fish to your aquarium that is neither 100% aggressive or considered peaceful, this article is for you.

Here are 7 semi-aggressive saltwater fish that you may want to consider.


1. Yellow Tang



The Yellow Tang is one of the most popular fish to see in saltwater tanks. They are also common to see in reef tanks as they are reef safe.  I have always had one in my tanks over the years. The keyword there is one. Yellow tangs are great tankmates for the most part if they are the only yellow tang in the tank. Putting 2 of them together in the same tank is not a great idea.

If you plan to keep more than 1 Yellow Tang in the same tank, the best way to accomplish this is to have a very large tank and introduce them together at the same time. This will give you the best chance for success.

Yellow Tangs are generally peaceful with other types of tangs such as the Hippo Tang and Vlamingi Tang. They will also get along with other peaceful tankmates like Clownfish and Cardinals. Overall these fish make for a stunning addition to your tank. They can be very peaceful for the most part, but very aggressive and terrorize other fish as well. You will need to be careful with the tankmates you choose for them. Yellow Tangs are considered to be semi-aggressive.

2. Flame Angel



The Flame Angel is a saltwater fish with amazing colors.  Although they are normally considered a peaceful fish, I listed them here as semi-aggressive as they can’t be in the same tank with other similar angelfish like the Coral Beauty.

If your tank is large enough and they are introduced at the same time, you might get away with it. But for the most part, I wouldn’t count on it. Also, you can’t have 2 male Flame Angels in the tank. They will fight to the death. Don’t even try it.

The Flame Angel does make a great tankmate for other non-angel type fish. For example, they will get along with most tangs, clownfish, and many others. They are also considered reef safe with caution, for the most part, they won’t bother corals but you have to watch them as they can pick at polyps, clams, and inverts.


3. Sailfin Tang



The Sailfin Tang is a surgeonfish that doesn’t play well with other Sailfins. They tend to be very aggressive with each other and according to Spruce Pets, they can even cut each other. They can also be bullied by other surgeonfish as well. They will generally get along with other fish providing they are not either another Sailfin.

The Sailfin Tang is considered reef safe and you shouldn’t have any problem with them bothering your corals. They are also safe with invertebrates. As with most tangs, they will make themselves available to be cleaned by cleaner shrimp and wrasses if they have a parasite. It is pretty impressive to watch them swim over to a cleaner to be cleaned!


Check out: 8 Saltwater fish that beginners should avoid


4. Harlequin Tuskfish



The Harlequin Tuskfish is a semi-aggressive fish that you might find very timid and shy at first, but once comfortable in your tank they will become quite active. They will normally get along with similar-sized species but are aggressive with other Tuskfish.

The Harlequin Tuskfish has really nice markings and colors and can make quite a showpiece in your tank. They are fun to watch and are considered to be reef safe. The biggest problem with them is as they grow, they can eat smaller less aggressive fish and invertebrates. If you plan to have inverts like crabs and shrimp, it’s probably not a good idea to have a Tuskfish.

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5. Emperor Angelfish



The Emporer Angel is one of the most visually appealing saltwater fish you can buy. They grow to be quite large and require a large tank of over 200 gallons to be housed properly. They have lots of personality and can become the dominant fish in your tank quite easily.

These fish are not overly common in the home aquarium due to their tank requirements and cost. In order for them to stay healthy, they require pristine water conditions. They are also recommended for fish only type saltwater aquariums as they are known to pick at certain corals. They can be kept in tanks with certain SPS corals, and you may get lucky with some LPS corals, but for the most part, I wouldn’t consider them reef safe.

Emporer Angels should be introduced to your tank last if possible as this will help with aggression. They will generally get along with other tankmates that are the same size providing they are not another Emporer. Other Angelfish will be ok with the Emporer as long as they are not similar in colors and sizes.


6. Damsel Fish



If you have been doing research on aggressive fish, I’m sure you stumbled upon the Damselfish. There are many types of damsels and some are more aggressive than others, but for the most part they are all considered either semi-aggressive or aggressive.

There are some very nice Damselfish that many hobbyists keep like the Yellow Tail damsel. These fish are quite colorful and do well in groups providing you have a large tank. If you plan to have just 1 Damsel, you can get away with a much smaller tank as they only grow to about 1-2″.

Mixing different types of Damsels in the same tank is not a good idea. They are very territorial and will fight constantly. The good thing is that Damsels will get along with other semi-aggressive fish like Yellow Tangs, Clownfish, and Dwarf Angels. If you have any timid and shy fish in your tank, don’t add a Damsel as they will most likely bully them to death.



What is the best saltwater fish for a beginner?

There are many great saltwater fish that you can have as a beginner. These include Clownfish, Tangs, Chromis, Coral Beauty, Dottybacks.

Can saltwater predator fish be kept with others?

Yes. Providing they are kept with other similar predatory fish.

Are saltwater tanks hard to maintain?

Not necessarily. It’s a good idea to have a regular maintenance schedule to keep everything in check. This includes water changes and making sure all equipment is working properly.