Salt or Fresh Water Ecosystem?

Most people that get into the aquaria hobby start with freshwater. You win a goldfish at the county fair, or inherit one from a neighbor that’s moving. Maybe you saw a pretty betta fish in a tiny cup and you just had to rescue it.

We’ve all been there. The people who keep that goldfish alive longer than a couple months get hooked (pardon the pun). You go to the pet store to find a companion and then all of the sudden you see the saltwater fish. Those fish are much more attractive. They’ve got bright colors and more interesting shapes – and what is the deal with coral? That stuff is so cool. Now you need a saltwater tank. This happened to me.

Salt Water Systems are Hard

You figure out pretty quick that saltwater tanks are a lot more work than freshwater ones. It’s not just adding some salt every now and then. Salt interacts with and affects the levels of other chemicals. It also requires different filters and equipment. All of these fish need specific temperatures and heaters in the water now?

Unfortunately, these problems extend to jarrariums. They’re exacerbated, even, by the small size of the jar. Chemical levels, salt included, are more volatile in containers with low volume. Saltwater species tend to be more picky about their surroundings. Many of them get sick or die quickly if salt levels stray from a narrow range. Tropical species are also accustomed to water with very little nutrients in it, and don’t do well when algae appears. You’ll need a heater and probably a carbon dioxide injector just for plants. Saltwater animals are accustomed to high levels of oxygen because of the constant churning of waves, so you’ll need a bubbler for them too. If you have anemones and corals, they are even stricter! They require very precise conditions to thrive.

salt water jarrarium

The sad truth: You won’t be able to make a low-tech jar (one without extra technology like filters or heaters) if you are using salt water. A hi-tech saltwater jar is possible, though difficult. You’ll have to do regular maintenance. It’s expensive to set up too; saltwater creatures and corals tend to cost a lot more than their freshwater counterparts.


If you choose to do a saltwater jar, remember: no vertebrates. Sorry, but Nemo will not survive in a 2-gallon jar. You’ll have to leave all those colorful fish at the pet store. However, if you can put in the effort, corals and anemones are as interesting and colorful as any fish. There are also an abundance of fanciful shrimp and snails. There’s always excitement and color in a saltwater jar. For simplicity’s sake, the guides on this site are written from the perspective of a freshwater system. All of the concepts are still applicable to salt, however.

Next up – choosing your jar!