Is it true that saltwater fish put in freshwater will swell up before dying?

Answer 1

Yes just the same as fresh water fish put in salt water would shrink
it has something to do with osmosis where fluids with lower concentrations of substances move to fluids of higher concentrations to balance and because salt water fish are used to not letting much in when they get no salt they swell!
look up osmosis for more info!





HERE:My attempt at explaining Osmosis and how it effects your fish.
OK for the benefit for anyone who cares, in biological systems many membranes are semipermeable so they allow for some particles to pass through but not others. Osmosis is the movement of solvent molecules but not solute particles through this membrane and it does it from a more dilute solution to a more concentrated one.
OK to try and put it in more simple terms, water is the solvent molecules and the stuff dissolves in the water (salts etc) are the solute particles. What happens is if you have a high concentration solution on one side of a membrane and a dilute one on the other, the solutions tend to want to equalize, so what happens is that the solvent (water in our case) moves from the dilute side to the concentrated side thus diluting it (and concentrating the side it left) until both are equal. This is what the osmotic pressure is.

All right, so with fish, you got lots of membranes. For example you have gills and skin and fins etc. etc. Now with freshwater fish, the insides are more concentrated with stuff then the water around them. Their bodies have salts and stuff in the form of blood, the foods they eat, and whatnot. So freshwater fish are constantly taking in water into their bodies due to osmosis (dilute water comes in to try and dilute their bodies). Therefore freshwater fish constantly have to be "shedding" water from their bodies in order to survive. This happens in several ways including urine and breathing to name a couple.

Now when you add salt to your tank water, it raises the concentration of salts in the waters around the fish and so the differences between the concentration of the water and the inside of the fish are reduced some and therefore the osmotic pressure is lowered. Less water is taken in so the fish doesn't have to work as hard to rid their body of this excess water.

This is one reason why adding salt to a freshwater tank can be helpful. Your sick fish is already stressed and weakened, so by lowering the osmotic pressure by adding salt, you help your sick fish by giving its body a little easier time in dealing with that problem and more energy towards getting better or healing itself.

Marine fish have the exact opposite problem. The ocean has a much higher concentration of salt in it than in the fish's body, so the osmotic pressure is constantly trying to draw water out of the marine fish. Therefore, to keep from dehydrating, a marine fish is always drinking water to replace lost water. Marine fish have ways of getting rid of the excess salt. So next time someone asks you "Do fish drink?" now you know the answer and it depends on if you are talking about freshwater or marine fish. ;)

Answer 2

Well not exactly. Salt water fish can be placed in fresh water for various reasons, mostly to kill parasites just as fresh water fish can be dipped in salt water for various reasons.

All animals need a certain amount of salt to survive.

The reason some fish normally live in freshwater and others live in seawater is that one or the other environment provides them with opportunities that have traditionally contributed to their survival. An obvious difference between the two habitats is salt concentration. Freshwater fish maintain the physiological mechanisms that permit them to concentrate salts within their bodies in a salt-deficient environment; marine fish, on the other hand, excrete excess salts in a hypertonic environment. Fish that live in both environments retain both mechanisms.

One important aspect of environmental variation is the ionic composition of bodies of water utilized as habitat. Chloride cells in the gills of marine fish produce an enzyme, called gill Na+/K+ ATPase, that enables them to rid their plasma of excess salt, which builds up when they drink seawater. They use the enzyme to pump sodium out of their gills at the cost of energy. Additionally, their kidneys selectively filter out divalent ions, which they then excrete. An alternative set of physiological mechanisms allows freshwater fish to concentrate salts to compensate for their low salinity environment. They produce very dilute, copious urine (up to a third of their body weight a day) to rid themselves of excess water, while conducting active uptake of ions at the

Somefish including salmon, lampreys, shad, sturgeon and striped bass can migrate between fresh and salt

Even mollies and guppies can go from salt water to fresh water.

To answer the question, no they will not blow up or swell up before dieing. They will be unable to breath and just die.

Answer 3

Not sure if they will swell up or not but they will die. Saltwater fish cannot live in fresh water.

Answer 4

Probably... I don't know for sure. You may want to Google that question if you're going to attempt doing it, though I wouldn't, and don't get a very clear answer. But they will die, yes. I hope I was of some help.

Answer 5

No! That's absolutely bogus! Think about it, if Mr. A lived in country A which is tropical, and if Mr. B put him in Country B which is snowy, would Mr.A swell up into a giant balloon before he dies? Hehe, I'll stop fooling around. In other words, I mean that whoever told you that, has told you nonsense. Hope I helped.. Byeee..

Answer 6

yes. I cant explain why but I am sure if you put saltwater in freswater it will dye.

Answer 7

yes