Over millions of years of evolution, fresh water fish have adapted to carry out osmoregulation. The body fluids of a fresh water fish are hypertonic compared with the surrounding water and therefore they constantly gain water by osmosis. Fresh water fish gain water through the lining of their stomach and their gut - the same as salt water fish. In order to maintain a water balance, fresh water fish have to constantly remove excess water. Their kidneys possess a number of adaptations which make the constant intake of water easy to cope with; their kidneys possess many large glomeruli allowing rapid filtration of the blood and the tubules reabsorb mineral salts from the glomerular filtrate back into the bloodstream, resulting in a large volume of very dilute urine. Using chloride
Over millions of years of evolution, fresh water fish have adapted to carry out osmoregulation. The body fluids of a fresh water fish are hypertonic compared with the surrounding water and therefore they constantly gain water by osmosis. Fresh water fish gain water through the lining of their stomach and their gut - the same as salt water fish. In order to maintain a water balance, fresh water fish have to constantly remove excess water. Their kidneys possess a number of adaptations which make the constant intake of water easy to cope with; their kidneys possess many large glomeruli allowing rapid filtration of the blood and the tubules reabsorb mineral salts from the glomerular filtrate back into the bloodstream, resulting in a large volume of very dilute urine. Using chloride