How to take care of saltwater fish?

You’ve probably heard that caring for saltwater fish is quite challenging. Unfortunately, this is true but with a clean tank, balanced water levels, and dedication, it’s definitely doable. The best way to care for your saltwater fish is by caring for the aquarium they live in. Here are a few things to keep in mind while creating the ideal habitat for your fish.


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Saltwater fish can only survive in very specific water conditions and have a narrow tolerance for changes. The first step towards caring for your fish is to mimic the natural conditions they live in. Seawater fish thrive in warmer conditions. Keep the temperature of the tank between 73°F – 82°F (23°C – 28°C), which is what it would be if they were in the ocean.


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The proper amount of salt must be dissolved in the water for your fish to survive. It’s best to match their natural habitat’s salt levels. Ensure your aquarium’s salinity is close to the ocean’s salinity (34 to 37 parts per 1,000 units of water). A refractometer comes in handy to measure your tank’s salinity level.

pH Levels


Ideally, the pH level of your tank must be set between 7.6 and 8.4. pH is the measure of acid or alkali in the water. Measure the pH levels in your tank using color-coded testing strips to ensure it meets the accepted standard.

Tank Size


The ocean is a vast expanse of water and for a fish that is used to such an environment, a large tank becomes a necessity. The tank must be at least 55 gallons to maintain proper temperature and chemistry over time. Larger tanks are also better if you have, for example, a clownfish, which become extremely territorial and will seldom stray from their area of choice. Saltwater also can’t hold the same amount of oxygen as freshwater. This is another reason why they need to be bigger.

Cleaning and Maintenance

Saltwater tanks require regular cleaning. Maintenance is key and the best way to care for your saltwater fish and ensure their longevity.

Quick Checks:

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  • Make sure your fish are uninjured and disease-free
  • Count your fish to make sure none have perished or leapt out of the tank
  • Check if the water temperature is between 73°F – 82°F (23°C – 28°C). This will indicate that any tank heaters you may have are functioning correctly.
  • Check if your tank water is clear. This ensures your filters are working well.
  • Check that your tank’s specific gravity is between 1.020 and 1.026 depending on the type of organisms in there. For example, clownfish and corals have similar characteristics and will survive in the same gravity measure. You can check with a hydrometer.

Note: specific gravity is the measure for amount of dissolved salts in your aquarium water in comparison to pure water.

Tank Water:

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  • Refill the fresh water lost to evaporation
  • Replace the water when it looks dark or smells

Check for leaks:

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You can find leaks by running your hand along the lines, pipes, tubes, and connections to make sure everything is plugged in properly, turned on and is not leaking. If you do find a leak, take corrective action by replacing the faulty part/system, checking if the pipe/tube is tightly screwed in, and all units are plugged into the circuit.

Remove Excess Algae:

Knowing what is causing all the excess algae makes it easier to get rid of it. Start off by moving your fish tank away from direct sunlight and controlling the light in the tank. Only keep the light in the tank on for 8-10 hours. Here’s also a more detailed article we wrote on identifying the type of algae your tank has along with how to remove it.

Overfeeding your fish can lead to increased algae growth as this increases the phosphate levels in the aquarium. Feed your fish small portions and watch them eat. Remove uneaten food promptly.

Water changes can also help keep algae at bay so perform them frequently. While you perform your water change make sure to vacuum the gravel as well this helps remove the algae.

When you see algae growing the best thing to do is scrub the surface or clean the glass with cleaning tools. Keeping live plants and algae-eating fish can also help control algae growth in your aquarium.

Protein Skimmer:


The protein skimmer collects all extra waste from the aquarium. You must clean the protein skimmer cup to prevent it from overflowing. You can do this by removing the collection cup and rinsing it clean. Wipe the protein skimmer’s neck to improve its efficiency.



  • Clean the filters as needed
  • Clean your pre filter sponges. This can remove any debris that is trapped in it.
  • Change at least 20% of the tank water. This maintains the quality of the water.


  1. Move your fish to a temporary tank, so you can do a full clean.
  2. Rinse the bottom material like rocks and plants with fresh water to remove all debris. It may take a few cycles before the water runs clear.
  3. Conduct filter tests
  4. Rinse the filter media
  5. Replace carbon filters as needed

Feeding your fish

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Understanding how much food and how often to feed your fish is important to their care. Feed your fish as much food as they can eat in five minutes. Provide the bottom fish and invertebrates tablets, pellets, and other foods that would sink to the bottom to reach them.

The best way to identify if you are overfeeding is by assessing how much food is left floating after all the fish have eaten. Be careful of this, overeating can stress your fish and cause detritus/waste to accumulate in the tank. This will result in degrading water quality.


It’s important to know how many fish your aquarium can support. Everyone wants plenty of fish, but the trick is knowing when to stop adding to your aquarium. An overcrowded aquarium causes more problems than you can imagine. It leads to low oxygen levels, more excretion, and more waste. Limited space makes fish extremely territorial and aggressive. More fish causes high levels of ammonia, nitrate, and nitrite, which also creates a toxic environment and stunts fish growth. All of the above will lead to the death of your precious fish.

Choosing your fish

The best way to care for your fish is by choosing species that can coexist with each other. The key to a healthy aquarium environment for your saltwater fish is doing your homework.

Some fish tend to be more aggressive, sensitive, peaceful, etc. You don’t want to house gentle fish with aggressive ones, as they may chase them or even prey on them. You also have to consider the compatibility between different types of fish. Some fish prefer to live on their own without tankmates. Know your fish before housing them together.


While caring for saltwater fish seems like a huge task, it can be made fairly easy by choosing the right fish and systems to care for them. The above information can guide you toward making the right choices and help you create an ideal environment for your fish to thrive in!