Saltwater vs Freshwater

When delving into the world of aquariums it is important to find which side you’re on, fresh or salt. The difference in maintenance, cost, fish choices and all the small nuances between saltwater vs freshwater aquariums makes it quite a difficult choice. Choosing the wrong type of aquarium can easily put people against the aquarium hobby, so we need to be sure when we decide if a saltwater or freshwater aquarium is more suited to us.

This main points to check will be:

The Advantages of Saltwater Tanks

In general saltwater aquariums will give you much more freedom when designing your tank. This is due to the huge variety of fish, corals and coralline algae that will bring color and life to the tank.

Saltwater Fish

Unlike freshwater fish, which have evolved while fighting with their habitat, saltwater fish have a near constant environment. How they interact with one another is as immensely important to their survival. This leads to my favorite aspect about saltwater fish.

Saltwater fish are more interactive

I am not talking about simple things like being surprised if you walk right up to the tank or when they swim up to the top of the tank when it is feeding time, as just about every fish will do these things.

Clownfish, puffers, tangs, mandarins, tangs and just about every saltwater fish will give a human glances every now and then, especially when you are closer to the tank. Many of the smaller, stationary fish like hawkfish, blennies and jawfish will actively keep an eye on both their tankmates and people. It is very easy to notice, as their eyes can travel around similar to how our own eyes move.

Larger fish like puffers and groupers even enjoy petting and actual interaction with the owners, but these are more rare cases.

In any event having your fish acknowledge and react to you makes the tank feel much more alive. I would say saltwater fish seem to be more intelligent, especially the larger ones, but that is just a personal opinion. Still the number of times my fish have bumped me or swam closer to watch me as I work on the tank is much higher for saltwater aquariums.


These are the main reason people get into saltwater tanks vs freshwater. Corals are absolutely stunning when done right and can easily be the centerpiece of a tank.

What makes corals so interesting is just how expressive they are. Corals will:

  • Extend when they are happy
  • Retract when startled or sleeping
  • become more dull when they are not getting nutrients
  • Bloom and multiply when perfectly cared for
  • Make a profit by selling the excess growth

When corals grow bigger than their owners want they will usually fragment, or cut up, the coral at the base. This allows them to take one large coral and make it into two smaller ones. What you do with the second one is up to you. People are always willing to buy these small ‘frags’ so you never have to worry about over growing coral.

Corals are living organisms that act like a mixture of plants and fish. The majority of their care will be strong light and occasional water supplements. They can also eat tiny fish and copepods, which are basically crustaceans the size of grains of sand.

When properly cared for coral will live basically forever.

Coralline Algae

Most people don’t think about coralline algae when talking about reef tanks, but they wouldn’t be the same without them. Coralline algae is what turns rocks into the pink, red and purple aquascape.

Coralline Algae behaves in two ways, depending on which type you get. The kind most aquarists get will grow across every surface, covering rocks, coral skeletons and even the aquarium glass.

The second type, which I have never seen happen unless the owner specifically got this kind, will grow out like a tree with tons of little, thin branches.

The Nice thing about Coralline Algae is that you don’t need to do anything to get it. As the tank ages it will slowly spread across your rocks and glass, making the tank look significantly more natural.

The Disadvantages of Saltwater Tanks

This section went longer than I expected it to. I just wanted to be sure nothing went unsaid. Saltwater tanks are not impossible but they certainly are more difficult. Saltwater tanks:

  • Cost much more to set up
  • Has more necessary pieces of equipment
  • Extra equipment means higher electricity bills
  • Require much more weekly maintenance, 3 – 4 hours a week being a good estimate
  • Are far more fragile than freshwater aquariums
  • Require a clean up crew, composed of snails and other bottom feeders
  • Have very precise water parameters to follow
  • Water changes are more tedious
  • The salt creeps out of the tank
  • The fish are typically more expensive
  • Live rocks can bring in hitchhikers, hidden eggs, that hatch into wanted or unwanted creatures

In addition to the equipment needed for a freshwater tank, a saltwater tank will need a protein skimmer ($80-$200), a powerhead/wave maker ($30-$100)to keep the water moving and salt ($20-$50). To make clean water you will need a reverse osmosis system($40-$200) which can make either a few gallons an hour or enough for the entire household. Additionally the saltwater testing kit, which is used to check the water parameters before adding any fish or corals to the tank, costs about $30 more than its freshwater counterpart. Then there are little bits and pieces you will use like a salinity meter for making salt water, buckets to mix the water in and pH adjusters

As saltwater does not need the air pump, air stone and tubing to aerate the water, which is instead done by the powerhead, you can subtract about $40 from the total difference. This means it will cost around $200 to $300 more to set up a basic saltwater tank. This is not including live rocks, corals or an extra strong light that would be necessary to grow the coral.

Fish prices can vary in both fresh and saltwater tanks, however saltwater fish tend to be more expensive and more fragile than freshwater fish. Again if you go to your LFS (local fish store) you will be able to find plenty of beautiful saltwater fish for under or around $20 each, but this is no where near as cheap as $2 neon tetras, $4 fancy guppies, $5 beta or $8 cichlids which are four of the more commonly kept freshwater fish. The cheapest clownfish I have ever seen were at a small fish store, which were selling at $24 each.

Some of the more exotic saltwater fish will easily break a thousand dollars. In general saltwater fish as much harder to breed in captivity, which is likely why we see such a jarring difference in price.

Luckily the clean up crew, often shortened to cuc, is not too expensive. You can often find snails or hermit crabs on sale in larger packs, which is useful when setting up a tank but can be too many if you need to add more.

Specialists, like the cleaner shrimp or crabs cost as much as the fish, but are not necessary to the tank. A lot of fish will attack shrimp so be careful if you look into them.

Water changes in saltwater tanks

Changing and making saltwater is much more difficult than freshwater. You should use a reverse osmosis filter on all of your water, which will separate your water into both very clean water and mineral packed water. The mineral packed can be used for gardening but is essentially waste water.

Once you have clean water you will need to add salt and adjust the pH of the water by measuring the pH, then adding an additive to raise or lower the pH.

While the pH is changing you would then add the salt to the water and have a powerhead mixing it for a few hours, measuring the salinity and adding more salt as needed.

As the water evaporates and splashes around in the tank the salt will start to creep out of the tank. This means salt will get on top of the tank, on the light and around the base of the fish tank. Salt can really damage flooring so you need to keep up on cleaning around the tank.

Finally hitchhikers come from eggs that were on rocks you added to the tank. These could be anything from shrimp, fish, octopus, crabs or snails. You won’t see many of these and not often, but I have had some take years to finally come out of the rocks. Surprise crabs can be a hassle when you have slow moving fish that scoot along the bottom of the tank. More often than not you will not want whatever hitchhikers you get.

Advantages of Freshwater Tanks

Simply put freshwater tanks are much easier to set up and maintain, which is key for those trying out a new hobby. If something is far more difficult than you are will to deal with then you won’t be getting anything out of it. The key advantages of freshwater tanks are:

  • Less equipment to buy
  • Hardy fish
  • Lenient water parameters
  • Lower cost on equipment, fish, food and electricity
  • Much less required maintenance
  • A wide range of plant life

As stated in the saltwater section you will be saving between $200 and $300 for a basic tank by going the freshwater route. For bigger tanks the cost does up very quickly for salt but not freshwater. The only thing freshwater tanks need that saltwater tanks do not is an air pump. Saltwater tanks substitute in a powerhead to aerate the water, but if your freshwater fish enjoy a current then you can use a powerhead in the freshwater tank too.

The fish themselves are very hardy, which means they will survive in sub-optimal water easily. This doesn’t mean you should abuse your fish. Their hardiness helps new owners get their tanks set up much more quickly and not lose their tank should they make a mistake.

One example would be the importance of pH and temperature for the two iconic fish: clownfish and betta fish.

Clownfish have an acceptable pH range of 8.1 to 8.4, temp range of 72F to 78F

Betta fish have an acceptable pH range of 6 to 8, temp range of 75F to 86F

While the pH should not swing dramatically overnight, it is far easier for saltwater fish to suffer if their tank is not constantly monitored. Meanwhile freshwater fish can almost have their pH readings completely ignored once the tank has been set up. Still, you should check your pH after water changes, as the strips to check this are very cheap and come with plenty per pack.

Freshwater tanks trade corals for plant life, which is much quicker to grow and has benefits to the tank. Plants will feed off of the nitrates in the water, which are the end result of fish waste. This makes water changes even less common. Additionally plants will grow significantly faster than coral and can be had for a fraction of the price.

Finally the cost difference of running freshwater is much lower than saltwater. Unlike saltwater, freshwater fish do not need:

  • Their water to run through a reverse osmosis system, making watcher changes quicker, easier and cheaper
  • Salt mixed into the water, which creeps out of the tank
  • Protein skimmers, which are very annoying to get running right
  • Clean up crews/bottom feeders

If you don’t want to spend a significant portion of your time tending to the tank, freshwater is the way to go.

Disadvantages of Freshwater

There are very few draw backs to freshwater tanks. If anything the negatives could be opinions.

Freshwater Tanks Lack

  • The wide variety of fish
  • Colorful corals

There are plenty of beautiful freshwater fish that come in different shapes and sizes, but they do not have the variety that saltwater does. However, if you know which fish you want in your tank already, the lack of variety may not even matter to you. Things like cichlid tanks and dwarf puffers are excellent displays to have in the home.

Corals are the real loss of having a freshwater tank, but they require so much work that many people would never even bother to have corals. This is another drawback that is either a big loss or something you won’t even notice.

One last drawback would be that freshwater fish breed too easily. Simply having different gender sword tails, mollies or platy fish will often result in new fry every few months. If the tank is large and has multiple types of fish these new born fish will likely be eaten, but you can expect one or two survivors every once and awhile. Be careful that these don’t lead to over crowded tanks.

Quick Summary

If you didn’t want to read the whole article or just wanted things summed up quickly then these are the main takeaways:

  • Saltwater has a bigger range of fish and corals, costs more to start and takes more effort to keep running
  • Saltwater tanks feel, in my opinion, more alive and interactive
  • Freshwater has a decent selection of hardy fish that won’t die easily
  • Freshwater tanks are easier to care for and are much more budget friendly

The Final thing I want to leave on this page are forums. Fish keeping can be difficult and a lot of issues will be very personal. In these instance using a forum to reach out to large, experience communities is vital. For saltwater tanks check out Reef2Reef and for freshwater look to Fishlore. You can also ask questions on any of my pages.

2 thoughts on “Saltwater vs Freshwater”

  1. It’s so weird that saltwater fish will acknowledge and react to you more than a freshwater fish might. What makes them more alert and aware of you? My daughter wants a fish tank, so I’ll definitely have to get some saltwater fish. I think she’ll love that they swim closer to you. I had no idea that fish could be curious.

    • I think a big part of it is their diet. In general carnivores/hunters have to pay more attention to each other. A lot of the commonly kept freshwater fish are omnivores while almost every saltwater fish is a carnivore.

      Some freshwater fish, like cichlids and puffers are known for being interactive and are also carnivorous fish.

      A personal thought is also that saltwater fish live deeper under water with red bodies, making them nearly invisible while stationary. They developed eyes that can scout their surroundings without moving, which allows them to keep an eye on us when we walk around the room. Since they are not hard to see in the tank the fish are more on display and can actively be seen watching us, making them feel a lot more interactive.


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