Compatibility of Saltwater Aquarium Fish

Clownfish in marine tank

Saltwater Aquarium Fish Compatibility

There are numerous significant variables to consider while choosing residents for a saltwater tank. You should carefully choose the fish you add to your tank depending on how you want it to appear or how it is currently set up. Although blending predators and prey isn't the only factor to consider, if you have a specific species or mix of fish in mind, you may need to make some adjustments to your tank or plan to ensure that everyone is happy in their new home.

Ideal Tank Conditions

All fish, regardless of their environment, require a nutritious food and clean water. However, not all species were designed to coexist in the same environment. Do your homework on what fish you would want in your ideal setup before bringing any fish home or even purchasing your aquarium.


Some fish species like to be surrounded by their peers, but others want space to call their own. If a species was collected in the wild or raised in captivity, it may have distinct requirements. are recognized for living in groups and sharing their area well. Damselfish require their own cave in order to thrive in your aquarium. These fish are infamous in the wild for attacking divers who go too close to their rocky habitats. The territorial damsel recognizes herself in the diver's goggles and attacks! This criterion is unique to each species.

And territory is more than just a location to hide and defend. Fish want space to move about from time to time. That lovely little golden puffer you put in a 60-gallon tank will develop into a 1-foot-plus-long monster that will require more than 150 gallons of water. Never put a fish in a tank and then say to yourself, "I'll get a bigger tank later," since the vast majority of people will not. Prepare ahead of time or skip that particular fish.

Water Flow

All fish are anatomically different and seek different environments. Fish in a tank with insufficient water flow are at danger of overwork or poor water quality. You may be straddling the line between too much and too little flow, depending on the species mix.

Many saltwater fish, such as tangs and triggerfish, can readily navigate their way around an aquarium and swim against the current. Some people even love the activity, and if you use a powerhead to uniformly distribute the food, feeding time will be less congested. Other less mobile species, such jawfish and blennies, cannot swim against a strong current for lengthy periods of time. They may dart out at feeding time, but they spend the most of their life buried in the substrate or in rocky outcroppings. To maintain appropriate water quality, water flow should be directed throughout the tank environment, but keep in mind that some areas may require lower flow.

Any decorations you put to your aquarium will change the way water flows through it. Because the reverberations bounce back on the edges of the tank, smaller and micro saltwater tanks are more vulnerable to excessive water flow. Add some tiny, neutrally buoyant tub toys or a ping-pong ball filled with water to your aquarium and watch where they fall in the tank to assess the flow. They should not gain substantial momentum and should not always finish up in the same area.


In keeping with the region, certain fish like to hide in various locations. Without a safe haven, they will get stressed and will most likely die from malnutrition and secondary diseases. Blennies, for example, like rocky outcroppings with shallow caverns, whereas damselfish prefer small caves buried away deep inside. Jawfish could use the substrate as a hiding place. They'll need soft sand rather than hard gravel since they'll be moving it around to build their subterranean dwellings.

Specialty Housing

Clownfish are the most vocal proponents of cohabitation with customized housing. Clownfish come in a variety of kinds, with some preferring to live in certain types of anemones. The anemones are kept free of particulates and diseases, while the clownfish have a safe place to rear their young and hide from predators thanks to this symbiotic relationship.

Keep in mind that keeping anemones and other soft corals in an aquarium has its own set of requirements and limits, so keep that in mind when planning your tank. To avoid being knocked off their rocks, they'll need particular light conditions and low-flow zones. And just because they're sessile doesn't mean they won't leave their chosen location if they don't like it.


If you intend to raise additional fish, you will require even more space! Breeding pairs will require a secure location to store their eggs, which might be a cave, a coral, or the edges of their tank. Some parents may keep the eggs in their jaws until the baby fish hatch, but they will become withdrawn. Some animals will guard their young with ferocity, while others may adopt a more relaxed attitude. Other animals are salivating at the prospect of a nice egg munch.

Be sure to do your research before starting a breeding program, keeping in mind you will need to find a new home for your new fish if your tank is not big enough.

Ideal Saltwater Mixed-Species Tank

What does your tank look like once you've taken all of the aforementioned factors into account? Is it too large for your needs? What type of décor and substrate would you require? Do you really want a breeding pair in that tank, which is already full?

The size of a mixed-species aquarium is usually the most important aspect. Whatever your setup or the fish you have, a larger aquarium with a greater water capacity is always the superior option. More water provides more padding for maintenance failures. We know you do your hardest, but there will always be occasions when something comes up and your tank is forgotten. That extra volume will keep your fish alive until you return.

Re-evaluate your priorities if the size of your tank has become too much for you to handle. Perhaps you might look for smaller fish with smaller territories? Or fish that don't require a cave network that disrupts your water flow? If you really must keep fish that demand a large tank but lack the room, join your local aquarium rather than imposing a condition that will not thrive.

Gold-Star Tankmates

These easygoing fish are happy in smaller territories and get along with many other species.

Banggai or Kaudern's Cardinalfish (Pterapogon kauderni)

These laidback fish have a slower swimming speed and may live in a range of environments. During the night, they may be found in their caves, while during the day, they can be seen swimming. They are easy to breed in captivity and eat a variety of foods.

Neon Blue Goby (Elactinus oceanops)

Don't be fooled by its little stature. This goby's electric blue colour makes it a lively addition to any aquarium. They don't require a lot of water and may occupy small caverns that larger fish overlook. They're great as a single fish or in pairs.

Ocellaris Clownfish (Amphiprion ocellaris)

Clownfish come in a variety of colors and sizes, making them suitable for a wide range of reef aquariums. These easygoing reef fish prefer to live in an anemone yet get along with a wide variety of fish. Clownfish are all male when they are born, but the largest fish in a group will transition to female.

Incompatible Tankmates

These fish do not play well with others and require lots of water. Careful planning is required to bring these fish home.

Clown Triggerfish (Balistoides conspicillum)

Triggerfish, often known as live rock and coral nibblers, require a tank with a minimum capacity of 300 gallons. Their beak can quickly destroy all of the pebbles you meticulously placed, and they require tankmates that are similarly massive and aggressive.

Goldbar Wrasse (Thalassoma hebraicum)

Wrasses come in a variety of personalities, but the colorful goldbar wrasse, with its characteristic golden bar behind its operculum, is one of the most aggressive. These fish, which require a tank of at least 125 gallons, are quite territorial and do not accept newcomers well. If you're putting them in your aquarium, do so last.

Black Banded Cat Shark (Chiloscyllium punctatum)

All sharks and rays require a large volume of water. Although some species are not very aggressive, they are more sensitive to poor water quality and inappropriate tank conditions.

Overall, there is no one right way to set up an aquarium. Do your research before buying anything to make sure all species will thrive in their new homes.