Freshwater vs. Saltwater Tanks: What’s The Difference?

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freshwater tank
Freshwater tanks, especially fully planted ones, are not necessarily easier to maintain. Matt Jones/Shutterstock

Setting up your first aquarium can seem like an overwhelming task. There are so many decisions to make: How much can you spend? How big of a system do you want? Freshwater or saltwater? Which animals? What kind of lighting? Which filter? What type of substrate?

Navigating all these questions can be confusing, but the whole process is much simpler once you choose between freshwater or saltwater. This article will outline some of the basic differences between the two and hopefully help you figure out which one better suits your wants and expectations.

There tends to be a common misconception with aquarists entering the hobby that you start with freshwater and then eventually make the switch over to saltwater. While saltwater aquariums pose challenges that freshwater systems do not and it is typically simpler to start with fresh compared to salt, there is absolutely no unwritten rule that says you need to go salty as you become more experienced. I have been keeping aquariums for nearly two decades and still maintain both types of systems because I find them to be equally rewarding and enjoyable, but for different reasons. It’s also important to keep in mind that it is completely up to you how time and resource intensive you want your aquarium to be. Both fresh and saltwater systems can be extremely low maintenance and simple, or they can be time consuming and expensive. It’s all up to you, but here are some basics to consider when choosing between the two.

Initial Setup

Overall, freshwater is cheaper. From the get go, saltwater will automatically be more expensive because you’ll have to purchase salt to mix into your water first in order to make it habitable for marine creatures. This isn’t a huge expense, but it is something you will need to monitor in order to make sure you maintain the proper salinity in your tank. Some fluctuation is fine, but large swings in salinity can be extremely stressful for marine fish and invertebrates. Since salinity won’t be a concern in a freshwater system, that is one major parameter that you don’t have to worry about.

Time Spent Monitoring

Generally speaking, saltwater animals also tend to be more sensitive than freshwater ones to specific water parameters, such as pH and alkalinity, meaning that you will need to not only monitor those factors but also have a way to modulate them if need be by way of additives and buffers. This equates to costs in both time and money. Many of the available salt mixes are satisfactory as is if you are planning to maintain a FOWLR (Fish Only With Live Rock) set up. But if the goal is to eventually add corals, especially hard corals, you will need to seriously consider how best to maintain a stable and ideal environment.

Availability Of Fish

Saltwater fish are more expensive almost across the board when compared to freshwater ones. Freshwater fish are indigenous to rivers, lakes, and streams around the world, and literature suggests that about 95 percent of freshwater fish are bred in captivity. Having a consistent source of readily available, captive bred fish pushes down the price, making freshwater fish relatively cheap.

Saltwater fish on the other hand are primarily collected in the wild. There are currently 330 species of marine fish that have been successfully bred in captivity, but the majority of those are not regularly available for purchase either in stores or online. Since many of our saltwater fish are still wild caught, this drives up the cost in relation to the supply, making them more expensive relative to freshwater fish.

Clownfish are a prime example of how breeding a species in captivity can quickly reduce the price. A pair of wild caught ocellaris anemonefish would have easily cost $100 or more in the late ’90s, but now you can purchase a pair of captive bred ocellaris for about $30.

Captive breeding is obviously good for making fish more affordable, but it is also far more sustainable because nothing is being taken from these natural aquatic environments. Tank bred fish are also adapted to aquarium life, making them much hardier in captive settings and far easier to feed because they have grown up eating prepared foods.

Simple Or Complex

As I mentioned earlier, you can make either setup as simple or complex as you want it to be. Saltwater aquariums with corals, anemones, and ornamental invertebrates require much more time and money to maintain than a comparably sized system with only fish and liverock. By the same token, a fully planted freshwater aquarium that needs additions of CO2 and particular lighting is much more challenging than a tank with fish and some basic plants.

Fresh and saltwater aquariums are beautiful and rewarding, but which one you choose to start with will depend entirely on personal preference. As is the case with all animal husbandry, the best thing you can do to make sure your first foray into fish keeping is a successful one is to do as much research as possible beforehand so you know what to expect. If you understand the pros and cons of both systems, you will be better equipped to make decisions that will have a positive outcome for both you and your aquarium.

Article Categories:
Fish · Freshwater Fish · Lifestyle · Saltwater Fish