Does My Fish Tank Water Need to Be Salted?

A common question that pet fish owners frequently ask is whether they should salt their aquarium water. There is no wonder why this question pops up every now and then, seeing as how certain fish species originating from the ocean and other saltwater bodies need salted water to survive. However, how do you tell whether your pet fish is a freshwater fish or a sea fish? How much salt should you add to the aquarium? What if you have multiple species of fish living in the tank?

These are all questions that we will answer in this article. So pay close attention because small mistake can mean major consequences to our underwater buddies.

Does my aquarium need salt?

In many cases, you should add a certain quantity of salt to your fish tank. Saltwater is essential to fish as it reduces your pet’s stress level by assisting in osmoregulation (maintains flui d balance). However, not all fish species need salt water, and for some the salt can act as a toxin.

Saltwater fish from the ocean and sea definitely need salt water to live. In short, a saltwater fish will die if it is exposed to fresh water for long periods. Saltwater fish will die of being over hydrated in fresh water, and freshwater fish will die of dehydration in salt water. This is due to the physiological structure of the fish’s skin.

For many pet fish owners, adding salt to your fish tank depends on where you live. Living in the Pacific Northwest of the US, which has extremely soft water, would require that you add salt for your seawater mates. If you reside in Southern California where the water is already pretty salty, then adding additional salt to your tank will do very little (assuming that you do not own a water softener).

Is my pet a saltwater or freshwater fish?

Some fish have evolved to the level where they can thrive in both saltwater and freshwater environments. However, not all fish have evolved to that stage, so it’s important to know whether your sea critter is a freshwater or saltwater fish. Below is a list of saltwater and freshwater fish species commonly kept as pets.

Saltwater Fish:

    • Surgeon fish
    • Clown fish
    • Marine eels
    • Lionfish
    • Scorpion fish
    • Marine angel fish
  • Damsel fish

Freshwater Fish:

    • South and Central American Cichlids
    • African Cichlids
    • Pleco Fish
    • Catfish
  • Betta fish

However, don’t rely on this very limited list to determine whether your pet fish comes from the sea or lake. To be completely sure, when purchasing a pet fish, consult with the pet store whether the fish belongs in fresh or seawater. If you already purchased a fish but are still unsure whether they belong in a saltwater or freshwater environment, how did you keep the fish alive long enough to still be asking this question? Seriously, take it to a vet or pet store for answers.

How much salt does my pet fish need?

How much salt does my pet fish needThe salt levels in your fish tank are referred to as salinity. Salinity is important when it comes to happy and living fish, and different levels above or below required salinity can lead to stress or death of our fish friends.

One rule of thumb is to actually taste your fish tank’s water. For saltwater fish, you want the water to taste similar or precisely like water you find in the ocean. This means adding lots of salt to large aquariums. However, just be sure that you don’t add too much.

However, you shouldn’t worry too much about precise measurements of salt in your fish tank. Your fish can easily forgive you for small deviations in reef tanks. A salinity of 34 to 36 ppt (parts per thousand) is a good target to reach for your saltwater fish.

I have more than one species of pet fish. What should I do?

If you have more than one species of fish and you want to combine them into one singular fish tank, do the proper research on the fish and their natural habitat before jumping the gun and dumping all your fish pets into a large aquarium.

By now, you should know that not all water is the same and not all fish species come from the same water environment. Salinity is an extremely important thing to consider when purchasing more than one species of fish.

If you decide to make a community aquarium, then make sure that the fish inside are either saltwater or freshwater species, or can survive in either environment. Below is a list of fish species that have evolved to survive both water environments. However, you may not want to keep them as pets since 1) you’ll need an enormous aquarium, 2) they can be dangerous, or 3) you’ll eat them before you keep them as pets.

  • Gulf sturgeon
  • Green sawfish
  • Sockeye salmon
  • Bull shark
  • Barramundi
  • American eel
  • Atlantic stingray

Bottom Line

So in the end, it’s important to know which fish species you want to keep as a pet and which environments they naturally come from. Putting a freshwater fish into a saltwater-filled aquarium will cause it to succumb to dehydration, and a saltwater fish placed into a freshwater-filled tank will drown it (surprisingly). Ask a vet, pet store, or other experienced people about whether your fish comes from the ocean or a freshwater source.

Keep track of the salinity of your aquarium. Taste the water for seasoning and determine whether it’s salty enough or not. Measure out 34 to 36 ppt of salt to water if you want to play it safe, but saltwater fish can survive if you deviate slightly from the measurements.

Finally and most importantly, never EVER mix freshwater and saltwater fish. One of the fish will die while in the (un)salted water, and you’ll have to bear the weight of murdering your pet fish until the day it takes revenge on you in fish heaven.