One of the great aspects of keeping a larger saltwater tank is it opens the door to a wider variety of fish you can keep.
Some people don’t consider a 100-gallon tank to be large, but I do. Most tanks of this size are 6 feet long and wide enough to keep some of the larger fish that you couldn’t keep in smaller tanks.
Another great thing about larger tanks is you can still keep small fish if you choose. I personally love seeing the mix of large and small fish in the same tank.
With smaller tanks like the 10 gallon, you are limited to small fish only with only a few in the tank.
With 100 gallon tanks, not only can you have larger fish, but you can have multiples and even larger schooling fish.
There are just so many more options with larger tanks.
A 100-gallon tank might have the dimensions of 72” x 18” x 18” or 60” x 18” x 21” or something along those lines.
Here are 6 of the best saltwater fish options for 100-gallon tanks.
- Yellow Eye Kole Tang
- Yellow Tang
- Flame Angelfish
- Pearlscale Butterflyfish
- Lyretail Anthias
Yellow Eye Kole Tang
The Yellow Eye Kole tang is one of the smaller tangs that you can keep. They will grow to around 7” maximum size. Other tangs like the Clown Tang can grow to be 15” and are not suitable for a 100-gallon tank.
The Kole Tang is considered to be semi-aggressive but for the most part, they are peaceful with other tank mates. Only 1 Kole Tang should be kept in the same tank and they should not be kept with other aggressive fish.
One concern with these fish is they can sometimes get a mouth injury during shipping. This will prevent them from eating diatoms and other algae that they need. Ensure there is no injury to the mouth area prior to purchase.
The Yellow Eye Kole tang requires plenty of mature live rock in the tank. This will provide the detritus and algae that they will constantly feed on.
These fish are common to see in the hobby and are not expensive when compared to some others.
Expect to pay around $89-$99 for a medium-sized Kole Tang.
The most popular tang to see in saltwater tanks is the Yellow Tang. These bright yellow fish can add a ton of color to your tank. They will grow to about 8” maximum and usually stay smaller than that. They require a 100-gallon tank when full grown and can be kept in smaller tanks as a juvenile.
The Yellow Tang does a great job of eating algae in your tank and should be fed a herbivore diet.
If you have a 100-gallon tank, only keep 1 Yellow Tang as they are known to bully another Yellow if not in a very large tank and added at the same time.
Check out more facts about the Yellow Tang here
If you are looking for a fish that isn’t so common and has a ton of personality, consider a Lionfish. These are a predator fish that are well suited for a 100-gallon tank.
They are not the best choice for a beginner and should not be kept with invertebrates. The Lionfish is a reef safe fish and can be kept with other tank mates providing they are somewhat aggressive and won’t fit in their mouth.
They will normally leave others alone if they fit those criteria. You can keep them in predator tanks as well providing they are suitable for your tank size.
There are different types of Lionfish that will do well in a 100-gallon tank including the Volitan Lionfish.
They are not as easy to find as other saltwater fish, but they are somewhat common.
There are a few Dwarf angelfish that are suitable for a 100-gallon tank. The Flame Angel is a great choice. These fish are very colorful and can be a showpiece in your tank. You can actually keep these fish in smaller tanks as well but a 100 gallon gives them plenty of swimming space.
If you plan to keep a Flame Angel, make sure they have plenty of live rock in the tank. Dwarf Angels will bully each other so it’s best to only keep 1 per tank.
It’s possible for multiples to get along in a 100-gallon tank but it’s risky. The Flame Angel is peaceful towards other fish and there are a variety of tank mates to choose from.
They are reef safe and can be kept with corals.
The Pearlscale Butterfly is one of the more unique fish for saltwater tanks. They will grow to around 5-6” and have crosshatch markings with yellow fins.
They are a great butterflyfish for a 100-gallon tank as they don’t get quite as large as some others. They are generally considered to be peaceful although they will not get along with other butterflyfish.
They are also reef safe and one of the few butterflyfish that can be kept with corals. It is possible for them to nip at invertebrates so use caution when keeping them together.
They are not as colorful as some other saltwater fish but they are easy to care for and will get along with most other tank mates.
The Lyretail Anthias is a stunning saltwater fish that can be kept as a single or in a group. They are wonderful schooling fish. In a 100 gallon tank, there is plenty of room for a school of Anthias until they are fully grown.
Then a larger tank of 125 gallons or more is needed. When keeping these fish, it’s important to only have 1 male in the group. Anthias are hermaphrodites and if the male of the group dies, the largest female in the group takes over as male.
The Lyretail Anthias is a very colorful fish and peaceful to other fish in the tank. They are reef safe and won’t bother corals in your tank. They tend to school towards the middle and upper part of the tank so ensure that they have plenty of open swimming space.
They are not considered to be a good fish for beginners as they have a very specific feeding requirement. They need to be fed small amounts of food a few times each day.
If you can comply with their feeding requirements and provide them at least a 100-gallon tank, they make a great choice.
Check out Lyretail Anthias care guide here
How many fish can you put in a 100-gallon saltwater tank?
The amount of fish you can keep in a 100-gallon tank really depends on the type of fish you are keeping. There is no set rule and you can keep more smaller fish than you can larger fish. Keep in mind the bioload of your tank and ensure proper maintenance on a regular basis.
Water changes are important for improved water quality and keeping parameters within limits.
On average you can keep up to 10 fish in a 100-gallon tank provided they are small to medium size. If larger, then you may only be able to keep 5 or 6.
There are quite a number of saltwater fish that are suitable for a 100-gallon tank. These are 6 of my top choices. Keep in mind that these fish may need a larger tank as they grow. Although they are suitable for this tank size now, always keep an open mind to upgrading if needed.
Any of the above choices will be suitable for a 100-gallon tank and should be compatible with each other if you wanted to keep 1 of each!