The term small saltwater tank is a relativistic comparison. What is small for one home or group may not be to another, but in general, any aquarium that is 30 gallons (113.6 L) in volume, or less, would probably be considered a small saltwater tank. A saltwater tank of 30 gallons (113.6 L) or less is sometimes referred to as a nano tank.
This article will look at the best fish for a small saltwater tank, starting with 30 gallons and working our way to 10 gallons. Any of these nano reef tanks would be a great addition to one of those small spaces in your home.
Best fish for a small saltwater tank: criteria for making the best choices
To make this list of the best fish for a small saltwater tank, they have to be:
- Peaceful fish
- Hardy fish
- Smaller fish, in terms of their size as adults
- Not aggressive (with one big exception at the bottom)
Most of the fish on this list would also be a good fit for a larger size aquarium as well, but the focus of this article is to help identify the best fish for a small saltwater tank.
50 Best fish for a small saltwater tank: 30-gallon aquarium size
You can target a maximum range of between 7 and 9 fish from the chart below of the best fish for a small saltwater tank that is 30 gallons in size.
| Saltwater fish type & number (7-9) | Alt 1: | Alt 2: | Alt 3 | Alt 4: | Alt 5: |
| Clownfish (1 pair) | Ocellaris clownfish | Orange skunk clownfish | Percula clownfish | Pink skunk clownfish | |
| Green chromis (1) | Instead of clown | ||||
| Dartfish (1) | Firefish | Purple Firefish | Scissortail | Zebra dartfish | |
| Shrimp and other gobies (1) | Clown goby | Court Jester goby | Two spot goby | Yasha goby | Black barred convict goby |
| Cleaner goby (1) | Neon goby | Yellow line goby | Shark Nose goby | Hybrid goby | |
| Small blenny (1) | Tailspot blenny | Two Spot blenny | Bicolor blenny | ||
| Fang blenny (1) | Canary blenny | Midas blenny | Striped blenny | Harptail blenny | Smith’s blenny |
| Cardinalfish (1) | Banggai cardinalfish | Yellow cardinalfish | Flame cardinalfish | Pajama cardinalfish | Long spine cardinalfish |
| Hawkfish (1) | Flame hawkfish | Longnose hawkfish | Falco hawkfish | Arc Eye hawkfish | |
| Fairy basslet (1), Chalk basslet (1), or Orchid Dottyback (1) | Royal gramma | Blackcap basslet | Chalk basslet | Orchid dottyback | |
| Jawfish (1) or Engineer goby (1) | Yellow-headed jawfish | Blue spot jawfish | Engineer goby |
Or
| Damselfish (up to 9) | Azure | Blue | Blue Devil | Blue Velvet |
| Damselfish continued | Three-stripe | Four-stripe | Yellow tail | Domino |
It is reasonable and common to keep a pair of clownfish that are the same species in the same saltwater aquarium. But it is generally best to limit your choices to only 1 individual from any other types of fish due to aggression between them.
It is also recommended to avoid mixing species within the same grouping–for example, do not mix Ocellaris and Pink Skunk clownfish.
Damselfish only for a small saltwater tank
Remember above, where I said there would be one exception? Here’s the deal. If you put several aggressive fish together without introducing peaceful fish, the aggression cancels out (sort of).
Another great option would be to skip the mixed community and build a Damselfish-only saltwater tank.
These are relatively small, beautiful, and hardy saltwater fish. They can be aggressive, but if they are kept in a shoal, or small group of similarly aggressive fish (for example, the other damselfish on this list), they tend to spread out the aggression amongst themselves so that individual fish may not be picked on.
The recommended number of damselfish for a tank this size would be up to 9 total fish.
Best fish for a small saltwater tank: 20-gallon aquarium size
You can target a maximum range of 5 to 7 fish from this list of best fish for a small saltwater tank for an aquarium that is 20 gallons.
When you compare this list to the 30-gallon list, these are the fish that are no longer suitable for the smaller saltwater tank:
- Yellow-headed jawfish
- Bluespot jawfish
- Engineer goby
- Chromis
- Chalk bass
- Midas blenny
- Striped blenny
- Harptail blenny
- Smith’s blenny
| Saltwater fish type & number (5-7) | Alt 1: | Alt 2: | Alt 3 | Alt 4: | Alt 5: |
| Clownfish (1 pair) | Ocellaris clownfish | Orange skunk clownfish | Percula clownfish | Pink skunk clownfish | |
| Dartfish (1) | Firefish | Purple Firefish | Scissortail | Zebra dartfish | |
| Shrimp and other gobies (1) | Clown goby | Court Jester goby | Two spot goby | Yasha goby | Black barred convict goby |
| Cleaner goby (1) | Neon goby | Yellow line goby | Shark Nose goby | Hybrid goby | |
| Small blenny or Fang blenny (1) | Tailspot blenny | Two Spot blenny | Bicolor blenny | Canary blenny | |
| Cardinalfish (1) | Banggai cardinalfish | Yellow cardinalfish | Flame cardinalfish | Pajama cardinalfish | Longspine cardinalfish |
| Hawkfish (1) | Flame hawkfish | Longnose hawkfish | Falco hawkfish | Arc Eye hawkfish | |
| Fairy basslet (1), Chalk basslet (1), or Orchid Dottyback (1) | Royal gramma | Blackcap basslet | Orchid dottyback |
Or:
| Damselfish (up to 7) | Azure | Blue | Blue Devil | Blue Velvet |
| Damselfish continued | Three-stripe | Four-stripe | Yellow tail | Domino |
Please keep in mind that we are pushing the limits a bit with respect to the hawkfishes and canary blenny. Some experts will set the minimum at 30 gallons in volume for these fish. You can never go wrong by erring on the side of a larger volume, but these fish should be alright in a 20-gallon tank.
Best fish for a small saltwater tank: 10 or 15-gallon aquarium size
In a 15-gallon aquarium, you can target a maximum range of 4 to 6 of these best fish for a small saltwater tank. In a 10-gallon aquarium, you can house the exact same fish species, just less of them. The maximum number of fish for a 10-gallon tank will be 5 or less.
Here is a summary of how this list changes as you scale down the plans from 30 or 20 gallons down to 15 or 10 gallons.
These fish were appropriate for a 30-gallon tank, but not below that:
- Yellow-headed jawfish
- Bluespot jawfish
- Engineer goby
- Chromis
- Chalk bass
- Midas blenny
- Striped blenny
- Harptail blenny
- Smith’s blenny
These fish were appropriate for a 20-gallon tank, but not below that:
- Flame hawkfish
- Longnose hawkfish
- Falco hawkfish
- Arc eye hawkfish
- Firefish
- Purple firefish
- Scissortail dartfish
- Zebra dartfish
- Orchid dottyback
- Canary blenny
- Flame cardinalfish
- Pajama cardinalfish
As you can see, shrinking the tank volume from 30 to 15 gallons reduces your options but still leaves you with a great list of fish to choose from. The best fish for a small saltwater tank that is 15 gallons in volume should come from the table below:
| Saltwater fish type & number (4-6) | Alt 1: | Alt 2: | Alt 3 | Alt 4: | Alt 5: |
| Clownfish (1 pair) | Ocellaris clownfish | Orange skunk clownfish | Percula clownfish | Pink skunk clownfish | |
| Fancy gobies (1) | Clown goby | Court Jester goby | Two spot goby | Yasha goby | Black barred convict goby |
| Cleaner goby (1) | Neon goby | Yellow line goby | Shark Nose goby | Hybrid goby | |
| Small blenny (1) | Tailspot blenny | Two Spot blenny | Bicolor blenny | ||
| Cardinalfish (1) | Banggai cardinalfish | Yellow cardinalfish | Longspine cardinalfish | ||
| Fairy basslet (1) | Royal gramma | Blackcap basslet |
Or:
| Damselfish (up to 7) | Azure | Blue | Blue Devil | Blue Velvet |
| Damselfish continued | Three-stripe | Four-stripe | Yellow tail | Domino |
Best fish for a small saltwater tank: an overview of the main types and care
Here is a brief overview of some of the best types of fish for a small saltwater tank.
Clownfish
Clownfish are THE MOST POPULAR type of saltwater fish. Their small size, gentle demeanor, gorgeous coloration, easy pair-ability (I made that word up, but you know…you can make a male/female pair easily), ease of feeding, and adorable waddling swimming motion make them one of the very first additions to most saltwater aquariums.
The four recommended clown fish for a small saltwater tank are:
- Ocellaris
- Orange skunk
- Percula
- Pink skunk
Clownfish are omnivorous and easy to feed. They will eat most live, frozen, and commercial flakes and pellets. Even though they stay very close to an anemone in the wild, it is recommended to keep them without an anemone in a saltwater tank.
Cleaner gobies
The cleaner gobies are another excellent fish type perfectly suited for a small saltwater tank. As their common name suggests, these fish occupy the niche of “cleaners” out on the ocean reefs, swimming around larger fish and picking off parasites, which is a fantastic and fun behavior to observe.
These best fish for a small saltwater tank are attractive, too, sporting a bold neon stripe that rivals the very popular neon tetra.
Even though they are cleaners, they should also be fed regularly with the rest of your fish. Due to their small size and small mouths, they do require smaller morsels of food but should otherwise take most foods readily.
The 4 recommended cleaner goby fish for a small saltwater tank are:
- Neon goby
- Yellow line goby
- Shark nose goby
- Hybrid goby
Cardinalfish
A few popular cardinalfish species make up some of the best fish for a small saltwater tank. Some of these fish can get relatively large for the relative size of the tank, but they are gentle swimmers that tend to just “hang out” in the water column checking things out.
I’ve had someone on a Zoom call (with a fish tank behind me, of course), confused about how my screen could be frozen (the fish behind me wasn’t moving) while I was still free to move. Sometimes, they just like to chill out and stare.
But, don’t let that description make you think they’re boring because they are not. They have gorgeous finnage, bold patterns, and some are super-colorful. In my experience, they are slightly more picky eaters than some of the food on this list, preferring soft, frozen foods like brine shrimp and mysis shrimp or live blackworms or brine shrimp over dry prepared flakes or pellets.
But they will attack those preferred foods with zeal, gulping them in as if the meal might otherwise get away.
The 5 recommended cardinal fish for a small saltwater tank are:
- Banggai cardinalfish
- Longspine cardinalfish (sometimes called Threadfin)
- Pajama cardinalfish
- Yellow cardinalfish
- Flame cardinalfish
Basslets
There are three basslet species that are some of the best fish for a small saltwater tank. They are:
- Royal gramma
- Blackcap basslet
- Chalk basslet
These remarkable fish tend to be wild-caught, but they are small, hardy, and very attractive fish. The Royal gramma and Blackcap basslet have a tendency to hang out upside down, which is another charming behavior to watch in a small saltwater tank.
The Chalk basslet is a bit more of an open water swimmer than the other two, which is why you see it recommended as one of the best fish for a small saltwater tank that is 30 gallons in volume, but not for any of the tanks that are smaller than that.
It is best to keep just one basslet per tank. They are compatible with most other fish on this list, except the dottybacks. You should select either a basslet or the orchid dottyback, but not both.
Dottyback
There are a lot of dottybacks are a group of fish you should approach with some caution. They are widely available, hardy, inexpensive, and most species have gorgeous coloration. Just like the damselfishes, however, they are aggressive.
The words pugnacious and scrappy come to mind when describing many species, despite their small size.
And they are also fascinating fish that have been successfully raised in captivity. Unfortunately, the only dottyback species that makes this list of best fish for a small saltwater tank is the orchid dottyback. Luckily, it is also one of the most popular.
The orchid dottyback is a slender, torpedo-shaped fish with a brilliant purple coloration. They like to swim around, and they will eat most foods. The one special trick to consider is to make them one of the last fish you add to your tank.
Aggression in fish is often about territory. An aggressive or semi-aggressive fish IN A TERRITORY will likely try to defend that territory against other fish it deems a threat. You can’t always predict which fish are a threat, but your fish will know and may take issue with some or all of them.
Being armed with that information (or is the more appropriate term being finned with that information?), we primates can use our gray matter to avoid creating that dynamic by letting the other more mild-mannered fish set up a territory first.
If you introduce the dottyback last, then the orchid is the interloper, and it never knew a tank world where it wasn’t happy for just a small plot of territory in the tank. This is not a bulletproof strategy. It certainly doesn’t neutralize the mixing of unmixable species, but for a fish like the orchid dottyback that is on the semi-aggressive bubble, it is probably enough to get the job done.
Shrimp gobies and other gobies
Perhaps no other fish on this list is better suited for a small saltwater tank than the gobies. These are small fish with prominent personalities and attractive colors. The shrimp gobies have a commensal relationship with shrimp. It is challenging to create that bond in captivity and not really recommended for a beginner. Still, if you see a bonded pair that is within your budget, they will undoubtedly become your favorite underwater friends.
They are also the perfect size for any size nano aquarium. The best goby fish for a small saltwater tank are:
- Clown goby
- Court jester goby
- Two spot goby
- Yasha goby
Chromis
The blue-green chromis is fun to watch in any aquarium because they might look blue, green, or both, at different times of the day in various positions in the tank. The fish isn’t changing color, but the iridescent color of their scales reflects light differently.
They are also hardy, inexpensive, and sometimes purchased as a group of 5 or more because they are naturally schooling/shoaling fish. Unfortunately, there isn’t enough room in a nano aquarium to have a shoal. In my experience, shoals of chromis dwindle in number more rapidly than their individual lifespans would suggest, anyway.
There is more aggression between individuals than one might think. They are also potentially incompatible with the clownfish species on this list. I have personal experience with a Chromis attacking a Percula clownfish so violently it wouldn’t eat and then once weaker picked the fins apart. The Perc had a tendency to hide. The aggression was a bit stealthier (like siblings not getting caught), but once I saw it, the aggression was undeniable.
I did separate the fish and reintroduce them into a larger tank a few years apart with some success, now that the Perc is a large female. They were added at the same time and squabble occasionally, but seem to coexist adequately.
Dartfish
The dartfishes are peaceful, almost graceful saltwater fish named because they will dart into the live rock crevices or any other cover they can find, when they get scared.
They are also peaceful to the degree of detriment to their survival. If they were in fish high school, they would be voted most likely to get stuffed in a locker daily. If your tank has a fish bully, it will pick on the dartfish, and the dartfish may jump out of the tank or starve.
The four recommended types of dart fish for a small saltwater tank are:
- Firefish
- Purple firefish
- Scissortail dartfish
- Zebra dartfish
Jumping is a hazard for any fish on this list, but having kept a handful of dartfish over the years, my experience is that they are extra jumpy. As in, accidentally leave the lid open overnight, and somehow they found the opening and jumped. One time I had a mesh lid that I didn’t notice was askew and not tightly closed, and they got out.
While this is anthropomorphic and unscientific, I did wonder if they’re more like hamsters planning a great escape than fish that jump because they are scared–but either way–the outcome is the same. Best to have a lid and use it every day.
The Firefish is probably the best value for the money of all the best fish for a small saltwater tank. They are stunning, inexpensive, and widely available.
Hawkfish
The hawkfish are the coolest fish on this list of the best fish for a saltwater tank. They’re cool, and they know it. They are invertebrate hunters by nature, so in a nano aquarium, they perch somewhere perfect for an ambush and watch EVERYTHING.
They’re also very attractive fish (most of them). The Longnose hawkfish looks like it belongs as a character in Candyland but is actually perfectly camouflaged for its natural territory.
A word of caution, however, about compatibility. Remember that part about them being invertebrate hunters? They are not compatible with snails, crabs, or shrimp.
It’s a bummer that you won’t be able to have adorable hermit crabs or graceful cleaner shrimp, but some things are worth a little sacrifice, don’t you agree?
The best hawk fish for a small saltwater tank are:
- Longnose hawkfish
- Flame hawkfish
- Falco hawkfish
- Arc eye hawkfish
Blennies
The Blennies are some of the most diverse groups of fish on this list of the best fish for a saltwater tank. The smaller blennies on this list are more substrate-attached bottom dwellers that like to perch and pick at the rocks. Fang blennies, like the canary blenny, are open water swimmers. Mine likes to tuck him-or-herself into the silicone beaded corner of the tank at night. It’s cute.
The best blenny fish for a small saltwater tank are:
- Tailspot blenny
- Two spot blenny
- Bicolor blenny
- Canary blenny
- Midas blenny
- Striped blenny
- Harptail blenny
- Smith’s blenny
- Forktail blenny
Best fish for a small saltwater tank for beginners
Most of the fish on this list are suitable for beginners, with a few exceptions. But if this is your first saltwater tank and you are interested in a curated list of the best fish for a small saltwater tank for beginners, here are a few great fish to start your journey:
- Ocellaris clownfish
- Any of the cleaner gobies
- Pajama cardinalfish
- Orchid dottyback
- Damselfishes
Most exotic, rare, or expensive
If money is no object, you might be looking for the most exotic, rare, or expensive fish on this list. If you are looking for the fish that will make your aquarium friends jealous, check out:
- Bluespot jawfish
- Blackcap basslet
- Purple firefish
- Yasha goby
- Midas blenny
Water quality
Maintaining stable, reef-like water quality is critical in a small saltwater tank. In one extreme way of thinking, in order to care for the best small fish in a saltwater tank, you need to first care for the water and make sure it’s perfect for them.
Here are the top 5 most important water parameters to develop the right water chemistry to keep the best fish for a small saltwater tank:
- pH: 8.1-8.4
- Water Temperature: 73-82 Fahrenheit
- Salinity: 1.025 Measured as specific gravity
- Ammonia: 0 ppm – more than that is a signal of a problem
- Nitrates: 0-20 ppm ideally, a fish-only tank can go slightly higher without problems
These water parameters are considered ideal because they recreate the water chemistry from their natural habitat.
You can learn about 5 other important water parameters in this article.
Best equipment for a small saltwater tank
All small aquarium systems have the same required equipment. You will need:
- A lid
- Lights set on a timer
- Pump to oxygenate and create water flow
- Temperature control (heater and/or chiller)
- Filtration
All-in-one setups generally have most or all of that equipment as part of the kit, or you can customize and piece together your system.
A small saltwater tank needs a lid.
There are two essential things to know about aquarium fish:
- Aquarium fish frequently jump out of saltwater tanks without lids
- Aquarium fish are notoriously bad at breathing air and living on your carpet
The simple yet effective tank lid helps keep those fish where they belong.
Lights
The best fish for a small saltwater tank will also need a light. If you plan to keep them with corals or other photosynthetic creatures, you will need strong ‘reef’ lighting. But if your plan, at least for the moment, is to start with fish-only, then just about any light will do.
Most people choose LED lights due to the longevity of the diodes and energy cost savings. High-end models are ultra powerful with specialized lenses and combinations of the light spectrum to optimize the growth of corals.
Lower-end models simply get the job done and light things up. They can sustain certain lower-light corals that are kept very close to the lights but otherwise are best left for fish-only tanks.
Whenever possible, set up your lights on an 8 or 12-hour on, 12-16 hour off cycle to create a relatively normal sunrise/sunset day period.
Filtration
Water filtration is a crucial aspect of keeping the best fish alive in a saltwater tank.
The three types of aquarium water filtration are:
- Mechanical: removing physical particles that don’t fit through a filter
- Chemical: using activated carbon or an ammonia-absorbing material to bond with chemicals and remove them from the water
- Biological: naturally occurring bacteria turn compounds that would otherwise hurt your fish into mostly harmless chemicals
In a small freshwater tank, all three filtration mechanisms are most commonly conducted in either a sponge filter, hang-on-back power filter, or canister filter. The back compartment typically has a filter in the all-in-one style small saltwater tanks, but many people run tanks without a commercial filter at all.
That doesn’t mean there is no filtration, just that the filtration step, primarily biological, happens in the tank. Live rock is used as a natural reservoir for the bacteria that do the filtering.
Many other small saltwater tank owners have equipment called a protein skimmer. A protein skimmer removes waste from the water using bubbles to pull particles and organic matter out of the water.
Importance of live rock in a nano reef tank
The ideal setup for a nano reef tank will have lots of live rock to help with the biological filtration but also as a structure to provide plenty of places for the fish to retreat into and hide when they feel threatened.
Conclusions
A smaller aquarium with saltwater fish displaying vibrant colors can be an attractive way to spruce up a small space in your home. It may also give you an enjoyable and challenging hobby for years to come. You may not be able to recreate your own version of Finding Nemo in a tank this size, but you can certainly still keep some beautiful fish.
To learn more about how to set up a saltwater aquarium, check out this article here.
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