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The Beginner Guide To Saltwater Fish

Table of Contents

If you are anything like me, you got into this hobby for fish (and corals!).  Whether you were on vacation in Hawai’i, have dived the Great Barrier Reef, or watched the David Attenborough narrated Blue Planet, something hooked you.

Keeping saltwater fish can be an extremely rewarding hobby, but also a hobby fraught with dangers.  Trying to replicate a tropical reef ecosystem in your home is no easy task.  If you haven’t watched my 30-part video yet on How To Set Up Your First Saltwater Aquarium, just click anywhere on this sentence.

Even with its challenges, there are steps you can take to set yourself up for success.  Before going out to purchase saltwater fish, give this article a read through.  It will give you the information necessary to make an informed decision, and hopefully set you down the path to a long-term, rewarding hobby.

I) Characteristics Of A Beginner Fish

© My First Fish Tank, 2019. Six Line Wrasse & Percula Clownfish

You may well be asking yourself, “what makes a fish a beginner fish?”  And that’s a good question.  Here are nine characteristics that make a fish a good “beginner” fish.

1) Hardy

Some fish are just tougher than others.  Who knows why… maybe they have better immune systems, maybe their slime coat is thicker, or maybe their natural environment more closely resembles our tanks.  Whatever the reason, a hardy fish is one that ships well, acclimates well, and is tolerant of changing water parameters.

All of the 10 fish at the end of this Beginner Guide are considered hardy, but that doesn’t mean invincible.  It just means they will have a better chance of survival.

Seachem Prime is great to use during acclimation to provide your new fish with a slime coat to prevent disease.

2) Inexpensive

Saltwater fish can be extremely, and I mean it, extremely expensive, like upwards of $1,000 for a single fish!  But then again, there are affordable fish as well.

A lot of factors go into the price of a fish, such as:

  • Where the fish is caught.
  • If the fish is captive-bred.
  • Where in the world you are located.
  • The ease of breeding in captivity.
  • How common the fish is.

I’m not encouraging you to just go out and buy the most inexpensive fish, but rather to consider the price.  When a fish dies, it can be a tragic experience for all parties involved, made especially worse when the death was not only premature, but also for an expensive fish.

3) Easy To Find

Most of us city dwellers have a LFS (local fish store) relatively close.  But for those of you country dwellers, you may not be so lucky.  Your only option may be to purchase a fish online, which usually entails overnight shipping which can be pricey.

Usually a fish that is easy to find, means it is relatively common in the hobby.  But just because it is easy to find, does not make it a beginner fish.  The easiest fish to find are usually Clownfish and Damselfish, both of which are great for beginners.

4) Easy To Acclimate

Sometimes a fish can look totally healthy in the store, but then within a day of coming home, it’s dead.  And you are left scratching your head as to why.

Some fish just don’t acclimate to change well.  Oftentimes, the water at your LFS is quite different than your tank.  The the salinity of the LFS water may be significantly less, and they may even have copper in their water.  

If you don’t acclimate your fish to the new environment slowly, it could get stressed out and die.  So a good beginner fish is one that can rapidly adjust to a new home.

5) Ships Well

Shipping may be the most stressful part of any fish’s life.  They are often rounded up from somewhere in the tropics, and shipped halfway around the world, only to be received at a wholesaler, and then re-packed and shipped across the country.

During their multiple flights, the oxygen content of the bag is getting less and less, and CO2 is growing.  Not only that, but the ammonia levels are increasing due to fish expelling waste.

A lot of fish are lost during shipping, and those that survive will likely need a lot of TLC to return to full strength.  So a good beginner fish is one that can survive shipping with minimal damage.

6) Captive Bred

There are a few species of fish that breed in captivity.  These fish are typically disease free, don’t have unwanted pests on them, and are trained from a young age to accept pellet food.  This can be especially useful for finicky eaters that would otherwise starve in the home aquaria.

Captive bred fish are also much more humanely treated, are not pulled from the reefs, and usually only have to be shipped once to the local fish store or your home.

Yes, they are more expensive but 100% worth the price.

7) Small

Sometimes small fish are really hard to keep, so I’m not trying to say that a small fish is somehow automatically a good beginner fish.

Rather, most beginners have smaller tanks, like under 60 gallons, and larger fish will just not do well.  For example, you could purchase a small Foxface Rabbitfish thinking it would be perfect.  But as it grows, it will quickly become over-sized for your tank and either die or need to be re-homed.

So a small species of fish is best for a beginner, because most beginners have small tanks!

Fluval Evo 13.5 gallon
A popular beginner tank, at 13.5 gallons can only hold a couple small (3" or less) fish.

8) Peaceful

Fish are usually grouped into one of three categories:

  • Peaceful
  • Semi-Aggressive
  • Aggressive

For example, Clownfish are considered semi-aggressive, because they will protect their territory and nip at other fish, but given enough space, they can also make great tank inhabitants and play nice.

The problem with keeping semi-aggressive or aggressive fish, is that they can easily bully another fish to death.  So the safest bet is to buy a peaceful community fish. That being said, several fish on this post are considered semi-aggressive, but I have found them to be able to live peacefully with many other creatures.  You will just need to watch your fish and remove any that are causing a problem.

9) Accepts Pellet/Flake Food

Some species are notoriously picky eaters.  They may only eat live food, frozen food, or they may need to eat five times a day!

So the safest bet is to purchase a species of fish that is either naturally not a picky eater, or a captive bred fish that has been fed pellets/flakes since their birth.

Once you get more experience under your belt, you will be able to keep those finicky eaters, but just don’t start with them!

A great beginner food- get the 1mm size since 2mm might be too large.

II) Aquarium Requirements

This is not the post to explain how to set up an aquarium… if you are looking for that click HERE to be redirected to my post and video “How To Set Up A Saltwater Aquarium.”

Rather, I just want to give you just enough information to get those gears turning when trying to decide on your first saltwater fish.

1) Size of Aquarium

You’ll still find the advice that says you can have 1″ of fish for every five gallons.  While that may be a good starting point, I think it’s pretty bogus overall.

A 20-gallon tank that is tall and thin vs. short and wide can hold different amounts of fish.  Surface area matters.

But let’s be realistic.  If you are going to have a 20-gallon aquarium, you can’t have more than a few small fish.  There are so many species out that that require at least a 60 gallon tank, so just be on the conservative side when buying fish, and shoot for too few instead of too many!

Waterbox Cube 20 Gallon Saltwater Aquarium
20 Gallon Waterbox Cube Aquarium

2) Filtration

The more robust your filtration, the more fish you’ll be able to keep.  What does “more robust” mean?  Well, it means a few things:

  • High turnover rate of entire water column.  If you have a 10 gallon aquarium, use a return pump that will turn over the entire water column 10-15 times each hour, meaning 100-150 GPH
  • Change mechanical filtration every day or every other day.  Fish food and waste will break down into ammonia the longer it’s left in the tank.  So catch those big particles and remove them before they have that chance!
  • Use a protein skimmer to collect all of the small pieces of organic matter that aren’t caught by your sponge or filter sock.
  • Use a lot of live rock and ceramic media to hyper drive your biological filtration.
  • Lastly, do weekly water changes of 10%-30%

Sound like a lot of work?  It is, so I recommend just keeping fewer fish!

Large HOB Power Filter & Protein Skimmer Combo
Filter Sock- Mechanical Filtration

3) Substrate

A substrate is anything that sits on the bottom of your tank like sand or gravel.  You don’t need a substrate to keep fish.  In fact, there are some in the hobby that encourage you not to keep a substrate because it will keep things cleaner.

But most of us end up with sand.  Sand is not necessary for most fish, but there are several species of fish that need a sandbed for their survival.  For example, a Sand Sifting Goby, you got it, sifts through the sand for its food.  Many species of Wrasses like to bury themselves.  And Dragonets need a large copepod population which a sandbed can help provide.

Fiji pink sand in 20 lb bag with close up of grain size
CaribSea Fiji Pink Sand

4) Saltwater

It doesn’t really matter which brand of saltwater you buy.  Most beginners just purchase pre-made saltwater from their LFS.  But if you are going to make your own, the only advice I’ll give is to choose a brand and stick with it.

The most important things for fish is to provide consistency.  Most fish can survive in a somewhat wide-range of salinity, but always shoot for 31.5-36 ppm.  If you plan on adding corals later, keep it at around a specific gravity of 1.026.

Always keep the temperature as close to 78 degrees F (25.6 C).

Check out my blog post on the “Top Five Beginner Saltwater Mixes.”

two red sea salt mix buckets side to side new in packaging
Red Sea Salt Mix- Great For Beginners

5) Hiding Places

No rocket science here, but many species of fish need places to hide in order to feel safe.  If they don’t have a place to hide, it can stress them out, and stress leads to sickness which leads to death.

Hiding places can easily be provided with live rock, but you can even place a few pieces of PVC pipe in your tank.  Not the prettiest option, but an effective one.

CaribSea Life Rock Shapes
CaribSea Life Rock

6) Lighting

While having the right type of lighting is absolutely essential for corals and anemones, it is not so true for fish.

Most fish can withstand a wide-range of lights, and don’t need the light for their food.  Too much light can stress a fish out, and fish certainly need a good portion of darkness each day in which to rest.

But if you just want to have a FOWLR system, then there is no reason to purchase an expensive programmable light.  Just go with an inexpensive LED, connect it to a timer, and voila, your tank is lit and your fish are happy.

I would try to run the lights for about 12 hours a day, maybe less.  Don’t be tempted to run them too much because you will get a lot of unwanted algae growth and your fish will not have enough time to rest.

Check out what lights I recommend in my post “Top Five Beginner LED Lights.”

Aqua Illumination Prime 16 HD LED Light

7) Cycling Your Tank

To learn how to cycle your tank, watch my 30-step video on “How To Build A Saltwater Aquarium”.

A lot of hobbyists cycle their tank by using fish.  I don’t recommend it because you are intentionally stressing your fish by placing them in an environment with ammonia.

So either be patient and wait the 4-6 weeks it takes, or use a faster fish-less method such as Dr. Tim’s.  You need to buy both of the products below to make it work, and you need to follow the directions to a tee.  I used this method on my neighbors build and it was fully cycled in 2 weeks.  But beware: this is not an instant cycle.  I don’t believe in an instant cycle actually.  But I think a two-week cycle is better than the standard six-week cycle!

III) Choosing A Healthy Fish

Well, if you don’t live near a LFS, then none of this section really matters to you.  You will have to purchase your fish online, so you won’t get to see it beforehand.  So in your case, do your research and make sure you are buying from a reputable seller.  I’ve bought from Live Aquaria before and been quite happy.

There are quite a few things you can look for, ask, and do to make sure you are getting the healthiest fish possible.

1) Ask About Quarantine Procedures

In an ideal world, your LFS will quarantine all new arrivals for 2-3 weeks before selling them.  If your LFS actually does this, you’ve hit gold and are quite lucky.  I’d say buy from them for sure!

Ask your LFS what their QT procedures are?  Do they have separate quarantine tanks?  Do they use any medications?  Do they treat with hypo-salinity? 

Or do they just put the fish immediately on display? Obviously the more QT they do the better.

white plastic bottle of seachem cupramine
Cupramine is a common fish only quarantine tank medication

2) Purchase Fish & Ask LFS To Hold For 1-2 Weeks

Once you’ve chosen your fish, ask your LFS if they will hold them for you for a week or so.  That way, if they die during that week, you know that a) it was not a healthy fish and b) you will get a refund or be able to choose another fish.

Not all stores will do this, but the good ones will.

3) Feed Fish

Any even remotely reputable LFS will feed the fish for you if you ask.  Healthy fish eat, stressed or unhealthy fish don’t.  If a fish is eating, it does not necessarily mean just buy it, but it is a good sign.

4) Buy Captive Bred Fish

There really is no downside to buying captive bred fish as opposed to live caught.  The only problem is that we haven’t figured out how to breed most species of fish, so your options are limited.

Captive bred fish are not only more hardy, but they are sustainably sourced and humanely treated.  That cannot be said, unfortunately, for most saltwater fish in this hobby.

You will have to pay more, but you are helping to save our reefs and treating your fish much better.

There will likely become a time when you will buy a live-caught fish, so do your best to learn about its source and wholesaler.  

5) Research The Source

I must admit that I don’t usually do this, but I should.  Not all exporters and importers of tropical fish are the same.  Ask your LFS who they buy from, and then do as much research as you can.  

Try to figure out what countries the fish are coming from.  What are the catching practices in those countries?  Do they use humane methods or dangerous chemicals? Are there strict restrictions on how many fish can be exported, or is a certain country known for over-fishing and destroying the reef?

What is the point of loving this hobby if our actions are destroying the things we love?

6) Observe Fish Behavior

This can be tricky as a beginner because you don’t necessarily know what “normal” behavior is.  Not only that, but “normal” varies between species.  Some fish are super curious and swim in the open and some like to hide.

But to the best of your ability, watch the fish for obvious signs of stress such as:

  • Rapid breathing.
  • Flashing (rubbing itself against a rock or hard object.  Could be a sign of disease).
  • Fear (it is normal to have some fear but a well acclimated fish should not hide all the time.
The recognized authority on fish disease and treatment

7) Check For Obvious Signs Of Injury/Disease

What are these signs?  Here are a few:

  • Frayed or torn fins- could be a sign of disease or aggression from other fish.
  • Missing scales – an obvious sign of severe stress, bullying, and/or disease.
  • Large growths- just like us, it is not normal to have a growth on the outside of your body.
  • White spots- a surefire sign of fish disease.

There are may more such as cloudy eyes, abrasions, white cotton looking patches, etc.  Just pull out your phone and search for your fish online to see what a normal healthy fish looks like.  If you have any doubt, don’t buy it.

IV) Acclimation, Quarantine, & Dips

It is always, always, ALWAYS best practice to drip acclimate your fish and use a quarantine tank.  Even though that is the case, most of us will haphazardly acclimate and skip the quarantine altogether.

For a full tutorial on how to drip acclimate your fish, watch my video “How To Set Up A Saltwater Aquarium.” To learn how to setup a quarantine tank, watch my other video “How To Setup A Quarantine Tank.” 

1) Drip Acclimation

At the very, very minimum, you need to drip acclimate all new fish.  It will take you about an hour, and has a couple steps.

The first step is to equalize the temperature between your tank’s water and the water in the bag.  The easiest way to do this is to turn off the lights in your tank and float the bag inside.  Float the bag for thirty minutes or until the temperature is almost the same.

The second step is to slowly add water from your display tank to the water from the LFS.  This usually involves using a bucket and some airline tubing.  Again, for a full demonstration watch the video by clicking this sentence.

Here are two options to help you drip acclimate your fish.  FYI, I use the fancy one on the left!

2) Quarantine Tank

I will (or have already depending on when you read this) create an entire Beginner Guide on how to set up and use a quarantine tank, but here is the brief version.  Why is it a good idea, no wait, why is it a great idea to quarantine all new fish?

  • It provides a stress free environment away from other fish.
  • You can spot fish disease easily.
  • Removing a sick fish is possible.
  • You can treat sick fish with medications that are not safe for invertebrates.
  • It prevents potentially life-threatening diseases from entering your display tank and killing your other fish.

Even given all of that, most of us think it too much of a hassle.  In fact I didn’t use a quarantine tank for the first several years of being in this hobby (shameful I know.)

Setting up a quarantine tank does mean having another 20-40 gallon tank, which for some is either out of their price range, too much of a hassle, or they just don’t have enough space.

I get it, but if you are not going to use a quarantine tank, at least consider doing a preventative dip (see below.)

3) Medicated Dip

There are tons of different types of medications and dips, and no single one will cure everything.  So please don’t read this and think that the following advice will cure your fish and prevent disease.  At best, it will help but that is all.  Nothing can substitute for a properly setup quarantine tank… nothing.

Freshwater dips as well as medicated dips can provide temporary relief from various parasites and infections, but often a sustained form of medication, administered over several days, will be required.

After drip acclimating your new fish, I would recommend using this two-step dip.

V) Top 10 Beginner Saltwater Fish

This is not some sort of exhaustive list, nor is it a list that will guarantee success.  But it is a good starting point when considering your first fish.  The fish on this list are known to be relatively hardy and easy to feed, so you are at least giving yourself a good shot at success on your first go around.

1. Clownfish (Ocellaris & Percula)

© My First Fish Tank, Percula Clownfish

There are currently around 30 recognized species of Clownfish, with Ocellaris and Percula being the most common in the aquarium hobby.  Clownfish are close relatives of Damselfish, and are semi-aggressive.  

Both Ocellaris and Percula clownfish are easy to find and inexpensive, thanks to many different captive breeding programs.  Clownfish are some of the easiest saltwater fish to breed in captivity.

You can purchase a captive bred Clownfish for under $20, which is not a bad price considering these fish can live for a decade!

As a beginner, I would recommend sticking to either the Ocellaris or Percula, as other species of Clownfish can grow quite large and be very aggressive.

Clownfish do not need an anemone to thrive.  Clownfish are best bought as a singleton or as a pair.  When purchasing a pair, it is best to make sure one of the clowns is smaller than the other.  The larger, more dominant clown will become the female.  All Clownfish are born male.

A 20 gallon tank would be able to hold up to two clowns. They are very hardy fish, but are susceptible to diseases such as Brooklynella, so proper husbandry is required.

2. Banggai/Pajama Cardinalfish

By Jens Petersen - Own work, CC BY-SA 3.0,

Comprising over 300 species, Cardinalfish mostly live in saltwater, although a few species are brackish or even freshwater fish.

There are many, many species of Cardinalfish available in the saltwater hobby, but the two most common that are great for beginners are the Benggai (Kaudern’s) and Pajama.

This peaceful fish can become slightly aggressive to smaller fish of the same family, and is best housed in a small school of 3 or more fish. 

Relatively easy to breed, captive bred Cardinalfish are more hardy than their wild caught counterparts.

They are slow swimmers, so watch for signs of aggression when first introduced to your aquarium.

They are really fun to watch, as they will often stay together in a group and seemingly remain motionless out in the open water column.

3. Firefish

By Jenny - originally posted to Flickr as Fire Goby, CC BY 2.0,

A goby-like fish, Firefish can add a bright splash of color to your tank.  Also known as a Dartfish, this species is small in size and not aggressive, except toward members of their own species.  That being said, you can purchase a mated pair that will live peacefully together.

Just be sure to have an adequate amount of hiding places, because when they feel threatened, they like to dart into a hole.  

Also know to be jumpers, don’t buy this fish until you have a secure mesh screen top!

Innovative Marine DIY Mesh Screen Kit

4. Yellow Watchman Goby

© My First Fish Tank 2019

Also known as a Shrimp Goby, these fish are awesome, in large part because of the symbiotic relationship they can form with various species of Pistol Shrimp.

They are bottom dwellers, and need a sandy substrate to burrow in, as well as plenty of hiding places within your live rock.

They will stay largely hidden, but poke their heads out and just stare at you!  They are also jumpers, so be sure to have a tight fitting mesh screen top on your aquarium.

They pair with several different species of Pistol Shrimp, and are fun to watch sharing a burrow together.

They are quite peaceful, and can live in a 20-30 gallon tank.

5. Six Line Wrasse

By Lonnie Huffman - Own work, CC BY 3.0,

A super hardy and colorful fish, you need to exercise a bit of caution before purchasing the species.  While they may be small in size, this Wrasse is highly territorial and will nip at smaller, more peaceful species, or other Six Line Wrasses.

If purchased for a small tank (20-30 gallons), you need to be very careful about adding other fish.  It would be best to house this fish with other semi-aggressive species like Clownfish or Damsels.

Affordable, easy to care for, and easy to find, this is a popular fish in the marine aquarium trade.  Just approach it with caution and be prepared to remove it if it continues to bully and nip at other fish.

I have a Six Line Wrasse in my 120 gallon tank, and when I added new Anthias and Damselfish, the Wrasse went after them for about a day.  But after that, they have lived together peacefully.

6. Flame/Longnose Hawkfish

© My First Fish Tank 2019
By Brian Gratwicke - Flickr: Flame Hawkfish Neocirrhites armatus, CC BY 2.0,

These fish are fun to watch in your tank.  Lacking a swim bladder, Hawkfish use their pectoral fins to perch on rock, sand, and coral.  

Relatively easy to find in the aquarium hobby, these fish are quite hardy, eat a variety of meaty foods, and have fun personalities.

They are quite peaceful, but can become aggressive toward members of their own species.

7. Blue/Green Chromis

By Adrian Pingstone - Photographed by Adrian Pingstone, Public Domain,

I have found Blue/Green Chromis to be quite hardy… if you get a good batch!  Too many times these fish are already sick when they reach the LFS, so be sure to follow the above steps for choosing a healthy fish.

Even though they are a Damselfish, Chromis are peaceful.  They do well in groups, and can live over a decade!

They are also some of the least expensive fish, and really easy to find.  They can grow up to 4″, so I would only house them in a tank of at least 30-gallons.

They are beautiful when schooling, and are a great beginner choice.

8. Azure Damselfish

By User:Haplochromis - Own work, Public Domain,

Another Damselfish, these bright blue and yellow fish are great for beginners.  They are semi-agressive, especially as they mature, so should be housed only with other semi-aggressive fish, in a 30 gallon or larger aquarium.

Inexpensive and easy to find, these fish are often captive bred.  A few dollars more a fish, buying a captive bred Azure Damselfish will help protect the reef and you’ll likely get a hardier specimen.

Great in small schools, be sure to provide plenty of hiding spaces as these fish will nip at others when threatened or to protect their territory.

9. Coral Beauty Angelfish

By Jenny (JennyHuang) from Taipei - Flickr, CC BY 2.0,

I hesitate a bit to recommend the Coral Beauty for beginners, primarily because they need a larger tank (60-70 gallons), and are known to nip at sps corals, lps corals, and softies alike.  But this is one of the few species of Angelfish that is captive bred, so is much more accustomed to the home aquaria.

A small species of Angelfish, the Coral Beauty is relatively peaceful toward other tank mates.  A grazing fish, be sure to provide plenty of live rock in your aquarium to allow this species to peck at food throughout the day.

10. Royal Gramma Basslet

By Smithsonian Institution from United States - Gramma loreto, Adult (Royal Gramma), No restrictions,

A great beginner fish, The Royal Gramma is not only beautiful, but great for smaller tanks.  While a peaceful species, it will attack other members of its own species.

A carnivore, this basslet will readily eat various prepared pellet foods.  It is territorial, and will chase other fish out of its hiding place amongst your aquascape.