Tag Archives: freshwater fish

Angelfish are among the more versatile aquarium fish.

admin    June 18, 2019   CATEGORY: Fish Facts

What are the Differences Between Freshwater Fish and Saltwater Fish?

On the surface, the differences between freshwater fish and saltwater fish are obvious: one lives in saltwater and the other lives in freshwater.  If you delve deeper into the issue, however, you’ll see there are actually several less apparent differences based on the biology and history of the fish.

In fact, you could say the two different types of fish are from different worlds.

The Main Differences Between Freshwater Fish and Saltwater Fish

Let’s start with some basic definitions. Saltwater typically refers to water found in oceans and seas, and freshwater is found in lakes, rivers, ponds, and streams. Freshwater only accounts for less than 3 percent of all the water on earth, but ironically, freshwater fish make up almost half of all fish species.

The differences between freshwater fish and saltwater fish include the idea that freshwater fish are more resilient.

Gourami fish are among the more popular fish for freshwater aquariums.

The way fish take in and eliminate water is perhaps the most significant difference between saltwater and freshwater fish. Fishes’ natural biological functions compensate for the environment in which they live in order to survive.

Both types of fish need salt in order to survive, but the way their bodies function is actually the opposite of what one may expect.

A saltwater fish’s body contains less salt than the water around it. In order to prevent dehydration, it takes in a large amount of water and secretes the salt through its gills. In other words, it’s saltwater in and salt out on a regular basis. Saltwater fish produce very little urine in order to hold onto the now more pure water created through this elimination of excess salt.

A freshwater fish, on the other hand, does hold onto the salt in its body because there isn’t as much of it in its environment. It takes water in through its skin and gills all the time in order to stay healthy. As a result, it produces much more urine than saltwater fish.

Other Notable Differences

There are many differences between freshwater fish and saltwater fish, like this black, gold, and white dotted clown triggerfish.

Saltwater fish, like this Clown Triggerfish, tend to be more colorful than freshwater fish.

  • Because the bodies of water that freshwater live in are smaller than oceans and seas, the body of water itself changes over time. As a result, freshwater fish may be tougher and can adapt to their environments easier than saltwater fish do. Saltwater fish that live in abundance of space are accustomed to a more stable lifestyle. As a result, taking care of saltwater fish in an aquarium may be a little more challenging.
  • Freshwater fish can be coldwater fish or tropical fish, while saltwater fish are almost all coldwater fish, which means they are comfortable in slightly cooler water.
  • Saltwater fish tend to be more colorful and diverse in their appearance as a result of how they live and behave in their natural habitat in the ocean or sea.
  • A few types of fish and other animals can live in either saltwater or freshwater, although it’s not common.

Brackish Fish

Scat fish are among the most common brackish fish.

Scat fish are among the most common brackish fish.

Some types of fish live in brackish water, which is where freshwater meets saltwater and where rivers flow into oceans. There isn’t a big selection of these fish, called brackish fish, in the aquarium hobby, although some hobbyists do keep brackish tanks.

Breeds of brackish fish include drum fish, tigerfish, Asian cichlids, halfbeak fish, flagfish, and scats.

TAGS: Brackish Fish, freshwater fish, saltwater fish,

How do fish drink water? Or do fish drink water at all? It's a question many people ask. The answer is different depending on if it is a freshwater fish or saltwater fish.

admin    January 19, 2019   CATEGORY: Fish Facts

How Do Fish Drink Water?

One question many people have asked is: Do fish drink water? Just like humans live in air and also breathe it, fish need to consume water to survive. How they get water into their bodies, however, is the interesting part.

Saltwater and freshwater fish take in water differently. They do need salt in their bodies to survive, but they can’t have too much nor too little. As a result, they naturally create a harmonious environment with the water around them through the process of osmosis.

Osmosis is based on the traveling of water across a membrane. For an optimal environment and to ensure the survival of the cells, osmosis must be regulated.

How Do Saltwater Fish Drink Water?

How do fish drink water? Although some fish do drink water, it's really based on the process of osmosis. An isotonic solution is one in which the level of salt is the same both inside and outside of the cell. In a hypotonic solution, there is more salt inside the cell than outside. Hypertonic refers to the level of salt being greater outside the cell than inside it.Saltwater fish take in water through their cells. In order to avoid taking in too much salt, however, they eliminate excess salt through their gills. In a normal environment, therefore, the bodies of saltwater fish are less salty than the water around them.

In other words, it’s saltwater in, saltwater out, all the time; saltwater fish constantly lose water out of their bloodstream through osmosis.

How Do Freshwater Fish Drink Water?

Freshwater fish maintain a higher level of salt in their bodies than the freshwater around them. Contrary to saltwater fish, freshwater fish are constantly gaining water into their bloodstream through osmosis. In order to eliminate excess water, they urinate frequently.

Does Water Get Into Fishes’ Mouths?

It’s natural that some water gets into fishes’ mouths. Once that water gets into a freshwater fish’s mouth, the water is directed out through the gills. Saltwater fish send some of the water that is coming in by their mouths through their digestive tracts and also over their gills.

What does all this mean regarding your fish tank? Most likely, if you regularly lose water from the tank, it’s due to evaporation. The fish aren’t really “drinking” large amounts of the water; instead, they’re circulating the water in and out of their bodies.

Contact Seatech Aquariums for fish tank maintenance in the greater Phoenix area.

TAGS: Fish Facts, fish tank, freshwater fish, saltwater fish,