People often wonder whether they should setup a freshwater or a saltwater aquarium. They have probably heard pretty convincing opinions on both sides of the argument (and yes, everyone has their own preference) which can make it hard to choose. I currently have both kinds of aquariums so I thought it would be useful to discuss the key differences between the two setups so people could better judge for themselves which one fits them better. This article is not meant to sway you one way or the other as I fully realize that each person has their own preference. Instead, it is meant as an overall view of their similarities and differences.

 

I do want to clarify one common misconception before we start. Many people seem to think that freshwater aquariums are for beginners and then when they get enough experience, they move onto saltwater. While it may generally be true that saltwater aquariums tend to require more expertise, there are plenty of very experienced freshwater hobbyist who simply choose to stay in the freshwater realm. Besides, there are numerous freshwater setups that can provide just as much of a challenge as a saltwater setup.

 

While we are generally breaking down the types of aquariums you can choose into two large categories – freshwater or saltwater – there are actually subcategories within each of these. These subcategories have a huge impact on aspects of your tank such as cost and maintenance.  

 

For freshwater, some of the subcategories include:

For saltwater, there are three main subcategories:

Throughout the article, I will point to how these subcategories impacts your experience within the freshwater or saltwater world.

 

The thing that most people think of when they think about the main differences between freshwater and saltwater is cost. There is a common perception that saltwater aquariums cost a good deal more than freshwater ones. To be quite honest, this is generally the case. Saltwater fish tend to be more expensive. Saltwater tanks tends to take additional equipment. Corals can add significantly to the cost. All of these things need to be considered, but do realize that cost is relative.

 

For example, a reef tank is probably going to be the most expensive of the saltwater aquariums. Therefore, if you wanted to keep the cost more in-line with a freshwater tank, you could setup a fish-only or FOWLR tank. You could also do DIY projects for much of the additional equipment required for saltwater or you could skip this equipment altogether as some people do (the recent push for nano-tanks has shown to some people that things such as skimmers or sumps are not required in all cases).

 

On the flip side of this, you can certainly make a freshwater aquarium very expensive. For example, if you have a heavily planted tank, the additional lighting, carbon dioxide, and fertilizers can add up fast. African cichlid tanks can require huge amounts of rock that can be equivalent to placing live rock in your tank in a saltwater setup.

 

As you can see, price is a relative thing. Yes, in general, saltwater aquariums are more expensive. But, as you can also see, this is not always the case.

 

It used to be the common belief that you could not have a saltwater tank under 50 gallons. However, this notion has recently been shown false. The rush of nano-tanks in the saltwater world went against many of the beliefs that saltwater people held dear and showed people that saltwater tanks can be as small as you like. In fact many manufacturers are now making 10-30 gallon all-in-one units (example: Nano Cube HQI) specifically for saltwater use.

 

Now, as with all tanks, the larger the aquarium, the easier it is to take care of, but the point here is that there is no longer this size difference between the two categories of tanks. You can have a 5 gallon saltwater tank or you can have a huge tank and the same goes for freshwater.

 

Saltwater tanks do require some additional work during water changes, mostly related to the fact that you have to mix the salt. This can be time consuming as the salt tends to dissolve slowly and requires you to buy a hydrometer to check the salinity level.

 

One way to not use up so much of your time is to mix your saltwater continuously by putting some water and some salt into a large bucket with a heater and a powerhead. You can then leave it for a while (24 hours minimum) and then when you need the water, the salt will already be dissolved. In fact, this is the preferred method rather than mixing it by hand and measuring the salinity right away. Salt can take up to 24 hours to dissolve so measuring the salinity right away is a bad indicator of what it will be in the end.

 

Some people get around mixing salt by buying large jugs of pre-mixed saltwater from their local fish store. You just need to know that this is more expensive than you doing it yourself in most cases.

 

Saltwater lighting can get VERY expensive. Many corals require metal halide lighting which not only is expensive to buy, but is also expensive to run. However, you can stay away from high-light corals and stick with power compact lighting which is a good deal cheaper than metal halide, but still more expensive than the “standard” fluorescent lighting found in many freshwater aquariums. You could also choose a fish-only aquarium where the only lighting requirement is what makes the fish look good. It should also be noted that saltwater corals generally require actinic lighting (not to mention the fact that this kind of lighting makes them really pop). Actinic lighting is not often used in freshwater setups as plants do not benefit from that portion of the spectrum and it can promote algae growth.

 

In the freshwater world, the planted tank is the only tank that really has a lighting requirement and even in these tanks, compact fluorescents are the lighting of choice. In all other freshwater aquariums, you only need the lighting that makes the tank and its inhabitants suit your tastes.

 

There is simply no substitute for a reef aquarium in terms of color. It is just a fact that there is more variety and a wider array of bright colored fish and corals in the saltwater world. The only thing that comes close, in my opinion, is an African cichlid tank (people who do not know much about fish often mistake my cichlid tank for a saltwater tank), but even these do not have the intense color differences found in a full reef tank.

 

Again, the edge probably has to go to saltwater here. While there are certainly enough freshwater species to ensure you never get bored, it just doesn’t compare to the huge array of very different looking fish and invertebrates found in saltwater setups. Being able to add corals and other odd creatures also adds to the variety found in saltwater setups.

 

Again, you can do a saltwater setup without a great deal of additional equipment, but the average saltwater aquarium does usually use more equipment than a freshwater setup. Examples of equipment many people use in the saltwater world that are not required in freshwater include:

 

While this may seem like a strange category, I felt it was important to put it in here because it is one of the main reasons I think saltwater tanks are so cool.

 

With saltwater aquariums, your tank is always evolving. When you put live rock or live sand in your tank, hitch hikers come along and you just have no idea what to expect next. Very rarely in the freshwater world (outside of snails coming with plants) do you see inhabitants in your tank that were not bought. It is really interesting to sit and watch your saltwater tank and see what is new. Now, along with this comes a negative because not all of these hitch hikers are good (examples: Aiptasia, bristle worms, mantis shrimps, etc.). It can be hard to remove some of these bad hitch hikers and can lead to added stress.

 

The closest I have seen to this in the freshwater world are tanks with fish that readily breed. My cichlid tank is pretty fun to sit down and watch because you can always see new fry hiding in little crevices. You also get to watch mating behaviors and courting. If you want a very dynamic tank, but in the freshwater realm, a tank with breeding fish or a tank with a definite hierarchy (example: African cichlids) can be quite interesting.

 

Another interesting dynamic in saltwater tanks is that you usually cannot see all the inhabitants at one time due to the large amount of live rock. You may see a fish poke its head out or something else swim behind the rock. It really adds to the natural feel of the tank.

 

Freshwater tanks can also be this way. I have a huge rock wall for my mbuna tank and the fish are constantly swimming in and among the rocks. A heavily planted tank also causes this to happen.

 

Similar to the fact that most (but not all) saltwater tanks are more expensive than freshwater, freshwater tanks are generally easier to care for. This is especially true when comparing a freshwater tank to a reef setup.

 

Again, there are counter examples (comparing a heavily planted tank to a fish-only saltwater), but generally the variables are less complex in a freshwater setup.

 

 

Obviously there is nothing in the freshwater world like coral. If you just love coral then saltwater is the way to go. My mother-in-law has a saltwater setup with two small clownfish and tons of coral species. She doesn’t really care for fish all that much, but she loves watching the different kinds of coral in her tank. Keep in mind though that with coral comes additional maintenance. Each one of your coral species may require a different diet, light level, or current preference. You must be willing to put in the time to properly care for these creatures. 

If you want to watch the miracle of birth in your aquarium then freshwater is probably the route you want to go. Very few saltwater species breed easily in captivity while many freshwater species breed like crazy.

I have kept both saltwater and freshwater and I must say that I enjoy each for different reasons. I know some people are very polarized on what they prefer, but I think each can be very entertaining as long as you do your research.