| How do fish drink water, proper aquarium osmotic | | | | and other animals have kidneys. The exact |
| function. | | | | amount of water and salt removed from their |
| ANSWER: Freshwater fish absorb most of the | | | | blood by the fish kidneys. The process of |
| water they need through their skin via osmosis (is | | | | regulating the amounts of water and mineral salts |
| the net movement of water through a selective | | | | in the blood is called osmoregulation. Fish which live |
| permeable membrane from a region of low solute | | | | in the sea (remember the sea is full of salt and |
| potential to a region of high solute potential), not | | | | other elements), but fish which live in freshwater |
| through their gills. The gills are for respiration. | | | | have the opposite problem; they must get rid of |
| Saltwater fish actually drink the water the live in, | | | | excess water as fast as it gets into their bodies |
| as the salt in the water is constantly pulling H2O | | | | by osmosis. Osmosis is an important topic in |
| from their bodies in a reverse respiration, this is | | | | biology because it provides the primary means by |
| why some fish such as catfish are sensitive to | | | | which water is transported into and out of cells. |
| salt in the water, but this is also why some fresh | | | | Generally salts, not just sodium chloride can affect |
| water fish are helped by salt to generate a | | | | osmosis. Magnesium can also play a major role |
| mucous slime coat on their skin which is | | | | too. Calcium can affect and just as importantly be |
| necessary for disease prevention. Proper | | | | affected by proper osmotic function. It is |
| electrolytes, magnesium and other elements are | | | | important to have a positive Redox which |
| important for slime coat generation. | | | | describes the ability for the loss of an electron by |
| Another note, because most freshwater fish | | | | a molecule, atom or ion to the gain of an electron |
| cannot drink their surrounding water (Salmon and | | | | by another molecule, atom or ion. Without this |
| others are exceptions), when you place these | | | | positive Redox Potential many minerals cannot be |
| freshwater fish in saltwater, they actually | | | | absorbed and properly assimilated. So it is very |
| dehydrate. | | | | important to keep a “positively charged” |
| Osmosis in fish; | | | | aquarium or a high Redox Potential (300 -400mV) |
| There cells must always be bathed in a solution | | | | via high dissolved oxygen levels, UV Sterilization, |
| having the same osmotic strength as their | | | | and proper electrolyte levels. |
| cytoplasm. This is one of the reasons why fish | | | | |