[ Sign my GuestBook ] - [ Read my GuestBook ]
[ GuestBook by TheGuestBook.com ]

Osmosis and Diffusion will take place via a semi permeable membrane ie. salt will move by diffusion from a stronger to weaker solution while the water molecules will move in the opposite direction. A fishes skin can be classed as a semi permeable membrane. The tendency in fresh water fishes due to the higher salt content in the body to that of the surrounding water is for the water to flow into the fish via the gills (osmosis) and salt to be lost via the skin tissue (diffusion). Fish counteract this natural process by the fishes Osmoregulatory system.

Osmoregulatory System

Fresh water fish have very efficient kidneys which excrete water very rapidly,salt loss is minimised by efficient re-absorption of salt from the urine before it is excreted and an active uptake of salt through the cells in the gills.

If the salt content of the surrounding water is increased either by the addition of salt or by increased hardness then this will reduce the load on the fishes osmoregulatory system. this can be especially beneficial to stressed or ailing fish.

Salt may reduce secondary infection but cannot totally prevent it. It is useful as a supportive treatment in the healing of wounds, but if the fish is affected by one or more aggressive strains of ulcer disease then salt on its own is most unlikely to solve the problem.

Plain salt will kill blanketweed, but once the salt sensitive types have died back the more resistive types may proliferate.

Salt at 0.3% level will reduce the toxicity of nitrite to fish, but will also reduce the efficiency of biological filters when first used. Plain salt has no effect on p.H. Only the use of mineral salts designed as p.H. buffers have any effect on stabilising the p.H. of pond water. It is best to use cooking salt or pure feed graded salt used for cattle. Table salt has higher levels of anti caking agents neither of which are desirable to fish. Vertually all salt in this country comes from the same source and has anti caking agents added (hexacyanoferrate) even if they are not listed on the bag. The above additives are normally added to a very small level (10 ppm). If you use salt below concentrations of 1% or less for long term treatment the level of hexacyanoferrate will still be just within U.K. drinking water standards and should be safe for fish. EMAIL me!

Main page