Let’s find the right fish for your tank
Beginner Saltwater Fish: How to Choose Your First Fish
Choosing your first saltwater fish should be fun. But before you fall in love with the brightest fish at the store, let’s make sure it will actually work in your aquarium. We’re going to look at how big it gets, where it likes to swim, what it eats, how it behaves, and what else you want to keep with it.
The short answer: choose behavior before color
Your first fish should fit the tank at adult size, accept prepared foods, and leave room for the fish you may add later.
What are we really looking for?
What Makes a Good Beginner Saltwater Fish?
When I call a fish beginner-friendly, I’m not just saying it is hardy. A great first fish should fit your tank when it is fully grown, eat food you can easily provide, and get along with the other animals you want to keep.
That last part is important. A fish can be tough as nails and still be a terrible choice for your aquarium. It might take over the entire tank, eat your shrimp, pick at coral, or grow much larger than you expected. So instead of giving you another top-ten list, I’m going to help you figure out which fish makes sense for your tank.
Before you compare fish
Make Sure Your Aquarium Is Ready
You don’t need a perfect aquarium, but the basics do need to be in place. If anything on this list isn’t ready yet, fix that first.
Here’s what to think about
8 Things to Consider When Choosing Your First Fish
A fish can be small, colorful, inexpensive, and easy to find—and still be wrong for your tank. Before you buy one, work through these eight questions.
How big will it get?
Stores usually sell young fish, so don’t judge by the size you see in the tank. Look up the full-grown size of the exact species.
How does it use the tank?
Some fish swim all day. Others hover in one spot, perch on rocks, or stay near a cave. Two fish of the same size can need very different amounts of room.
What kind of home does it need?
Does it need a sand bed, a deep cave, open water, lots of rock, or a covered tank? Build the home before you buy the animal.
Should it live alone or with a partner?
Some fish do best alone. Others can be kept as a compatible pair. Don’t buy three just because somebody called the fish a schooling species.
What does it eat?
Make sure you can easily buy the right food. Then think about how the fish eats. A shy fish may go hungry when it lives with fast, aggressive eaters.
How much waste will it add?
Big fish and heavy feeding create more work. Your filtration and maintenance routine need to keep up with the full-grown animal.
Will it bother your coral or invertebrates?
Some fish pick at coral, hunt shrimp, move sand, or harass snails and crabs. “Reef safe” is a good starting point, but it is not the whole answer.
What happens if it doesn’t work out?
Even a carefully planned fish can surprise you. Know whether you can catch it, separate it, return it, or find it another home.
Start with the tank you own
What Fish Work in Each of Our Three Beginner Tanks?
A fish that works beautifully in a 45-gallon aquarium may be a terrible choice for a 5-gallon tank. Here’s how I would approach each of our three builds.
I would skip the fish
I know that may not be what you wanted to hear, but 4.8 gallons gives a fish almost no room for swimming, territory, waste, or mistakes. This tank makes much more sense as a coral and invertebrate aquarium.
There are a few tiny gobies that experienced hobbyists keep in tanks this small. But for a first saltwater aquarium, I would enjoy the coral and invertebrates instead of trying to squeeze in a fish.
Keep the fish list simple
A single captive-bred ocellaris clownfish is a great option. A carefully selected pair can work too, and a small goby gives you another direction if clownfish aren’t your thing.
Here’s the important part: those are different plans. I would not automatically add a clownfish, a goby, and then keep going. Pick the fish you really want and build the tank around it.
You have room for a small community
This is where your options really open up. You can choose fish that use different parts of the tank—a goby near the bottom, a firefish hovering above the rock, and maybe a clownfish with its own territory.
That is only an example, not a shopping list. Plan the whole group first so you don’t accidentally make your first fish the boss of everything that comes later.
Let’s look at some actual fish
Beginner Saltwater Fish I Would Actually Consider
This is not a best-to-worst ranking. The green choices are usually easier to build around. The yellow choices can still work, but they come with a bigger warning that you need to understand first.
| Fish | My take | What it needs | How to keep it | Biggest warning | Where it fits |
|---|---|---|---|---|---|
| Ocellaris clownfish Amphiprion ocellaris | Great option | Open room, rockwork, and a place it can call home. | Keep one or choose a compatible pair. Most readily accept prepared foods. | Clownfish can get territorial. They do not need an anemone. | HelloReef 15 or JBJ RF-45. |
| Firefish Nemateleotris magnifica | Great option | A safe hiding place, open water, and a tight-fitting lid. | Give this shy fish time to eat before faster fish take everything. | Firefish jump, and aggressive tankmates may keep them hiding. | A covered JBJ RF-45 is the easiest fit. |
| Yellow watchman goby Cryptocentrus cinctus | Great option | Stable rockwork, a suitable bottom area, and the right substrate. | Make sure food reaches the bottom. It does not have to be paired with a shrimp. | Another bottom-dwelling fish may want the same territory. | Possible HelloReef alternative; very good JBJ RF-45 option. |
| Tailspot blenny Ecsenius stigmatura | Great option | Rock perches, hiding holes, and places to graze. | Watch it eat and offer a varied diet instead of expecting it to live on algae. | It is not an automatic algae cure, and individual fish may bother coral. | Carefully planned HelloReef 15 or JBJ RF-45. |
| Banggai cardinalfish Pterapogon kauderni | Think it through | Calm open water with nearby shelter. | Buy captive-bred when possible and decide whether you want one or a known compatible pair. | Don’t buy a random group. They can become surprisingly aggressive with each other. | JBJ RF-45. |
| Orchid dottyback Pseudochromis fridmani | Think it through | Plenty of holes, ledges, and places to get out of sight. | They are easy to feed, but I would plan around their territorial behavior. | An orchid dottyback may bully shy fish or fish with a similar body shape. | JBJ RF-45, usually added later. |
| Chalk bass Serranus tortugarum | Think it through | Rock shelter and enough room for the full-grown fish. | Make sure it gets enough food without overpowering smaller, shyer fish. | Its mouth and hunting instincts matter around tiny fish and invertebrates. | JBJ RF-45. |
A closer look
Why These Four Fish Are Good Places to Start
None of these fish is perfect for every aquarium, but each one can make a very good first fish when its basic needs are met.
Ocellaris Clownfish
Great option
There is a reason clownfish are so popular. Captive-bred ocellaris clownfish are easy to find, usually eat almost anything, and have a ton of personality. Just remember that clownfish are related to damselfish, and they can become protective of their favorite corner.
- This fish makes sense if
- You want one main fish—or a carefully chosen pair—and you have room for the territory they may claim.
- I would wait if
- You are buying two random clownfish or think you also need an anemone right away. You don’t.
Firefish
Great option
Firefish are beautiful, stay relatively small, and spend a lot of time hovering where you can see them. The catch is that they are shy and they are incredible jumpers. A tight-fitting lid is not optional.
- This fish makes sense if
- Your tank is completely covered and the other fish will give it enough peace and time to eat.
- I would wait if
- Your lid has gaps or you already plan to keep an aggressive fish that may scare it into hiding.
Yellow Watchman Goby
Great option
A yellow watchman goby spends most of its time near the bottom instead of racing around the entire tank. That makes it a really interesting fish to watch and can help spread your fish into different parts of a larger aquarium.
- This fish makes sense if
- Your rockwork is stable, the bottom is set up correctly, and you will make sure food reaches it.
- I would wait if
- Another fish already owns the bottom or you are counting on the goby to survive on whatever food happens to fall past everybody else.
Tailspot Blenny
Great option
Tailspot blennies stay small, perch on the rocks, and have an almost comical amount of personality. They may graze on algae, but please don’t buy one just to fix an algae problem. It still needs a real diet.
- This fish makes sense if
- Your tank has rock perches, hiding holes, some established grazing, and you are willing to feed it properly.
- I would wait if
- The tank is brand new or the entire plan is “the blenny will eat the algae.”
These fish come with bigger warnings
Four Hardy Fish I Would Not Automatically Recommend First
I’m not saying you can never keep these fish. I’m saying their hardiness can hide a problem that makes the rest of your aquarium much more difficult.
Hawkfish
Hawkfish are tough, full of personality, and really fun to watch. But they may eat ornamental shrimp and other small invertebrates, which can ruin the reef community you were planning.
Damselfish
Damselfish are some of the hardiest fish you can buy. Unfortunately, some are also extremely territorial. That inexpensive first fish can become the fish that attacks everything you add later.
Coral Beauty Angelfish
These are beautiful fish, but they need more room than our smaller builds provide and may pick at coral. I would not call one a simple, universal beginner choice.
Sunrise Dottyback
They are colorful, hardy, and easy to feed. They can also be territorial. I would only add one after planning the other fish and making sure there are plenty of hiding places.
Take a close look before you buy
How to Choose a Healthy Saltwater Fish
Once you have chosen the right species, you still have to choose the actual fish. If you’re buying from a local fish store, slow down, watch the fish for a few minutes, and ask a few questions.
The final decision
So, Is This Fish a Good Choice for Your Tank?
By now, you should end up in one of three places. And yes, “not yet” is a perfectly good answer.
Yes, this fish makes sense
It fits the tank when fully grown, has the right home and food, works with the rest of your livestock plan, and looks healthy. You also know what you’ll do if something changes.
Almost—but fix this first
Maybe you need a better lid, another cave, a different feeding plan, or more time for the tank to settle. Take care of that one thing before you bring the fish home.
No, choose a different fish
If the fish will outgrow the tank, fight with something you really want, appears unhealthy, or leaves you with no backup plan, it is not the right fish. There are plenty of other great options.
Keep planning
What Should You Do Next?
