The necessary vitamins are probably supplied in sufficient amounts when fish are given a varied diet, so vitamin supplements are usually unnecessary.
There are, nevertheless, situations when doses of vitamins in empirical quantities do seem justified – when certain species do not deposit fertilized eggs, for instance, or in periods of food scarcity when the animals can not be given a varied diet.
In such cases, a multivitamin preparation can be added to the food in very small quantities. The correct dosage depends on size and species. If certain fish species prove difficult to maintain in captivity because of susceptibility to skin infections, a relatively high dose of vitamin A can be given.
There may be other situations in which the use of vitamins appears justified, but for a normal community aquarium fed a varied diet, extra doses of vitamins seem superfluous and inadvisable.
Can I try to give my fish the vitamins that are available for humans, dogs, or cats? The answer is NO; fish and other invertebrates have other nutritional needs than humans or other mammals. Humans’ vitamins and minerals are in much higher concentrations than what fish need, and this could kill them
What Vitamins Do Fish Need?
Vitamin A and carotene
Beef and fish livers, crustaceans, arthropods, egg volk, algae, lettuce, spinach, water plants.
Vitamins B2 and B6
Crustaceans, beef, beef liver, fish, mussels, chicken eggs, spinach, lettuce, yeast.
Pantothenic acid, niacin, and vitamin B12
Green, brown and red algae, lettuce, yeast, beef; beet liver, egg yolk, mussels.
Yeast, beef liver, egg yolk. wheat germ oil.
Green algae, water plants, lettuce, spinach, beef liver, fish eggs.
Earthworms, mealworms, tubifex, egg yolk, snails, fish liver, water fleas, shrimps.
Green algae, lettuce, spinach, egg yolk, wheat germ oil.
beef liver, lettuce, spinach, water fleas.
What Minerals Do Fish Need?
Minerals that play a part in metabolic processes are calcium, sodium, potassium, magnesium, chlorine, iron, copper, manganese, sulfur, and phosphorus. It would take us too far afield to discuss extensively the role of these elements in the fish’s body, so we shall make only a few remarks on the subject.
Sodium and potassium control muscular function, regulate body fluids, and are involved in the conduction of nerve impulses.
Calcium not only constitutes the most important element of the skeleton, but is also important in many bodily processes such as reproduction, and muscle, nerve, and heart function.
Magnesium is necessary for bone building, nerve and blood function, growth, and also active in several enzyme systems.
Phosphorous, too, is involved in the formation of the skeleton and regulation of body fluids and active during the digestion of carbohydrates and in fat and protein metabolism.
Chlorine is a component of gastric juices and urine and regulates blood and cell fluids. Sulphur is important as a component of several essential amino acids.
In addition to these minerals, which the body needs in fairly large amounts, several so-called trace elements are necessary. Hardly anything is known about their role in the lives of fishes, but we do know that a few are indispensable. Among these are iron, iodine, copper, manganese, and cobalt.
Iron is a component of red blood corpuscles and is important for oxygen transport. It is found in the thyroid gland, where it is essential for thyroid health – the thyroid regulates metabolism – and for normal growth.
Minute quantities of copper are involved in the manufacture of blood and some enzymes. Manganese, like magnesium, is probably an activator of certain enzymes.
Finally, cobalt is a component of vitamin B12 and, thus, involved in blood production. Other trace elements have been demonstrated in the bodies of fishes, but we know nothing yet of their possible functions.
To conclude, certain vitamins and mineral elements are indispensable for growth and skeleton formation. They also serve as building blocks for the blood, enzymes, and hormones and play a role in such physiological processes as digestion and respiration.
As dissolved salts in the body fluids, for instance, they determine the osmotic pressure and pH of blood and the contents of body cells. If the diet is lacking in these mineral elements, deficiency symptoms, and in many cases death, will result.
Several vitamins and minerals can be assimilated directly from the water through the gills, so the fishes are not completely dependent on their food.
Chances are that a varied diet will prevent any mineral deficiencies. It is inadvisable, therefore, to experiment with these substances. In small quantities, the trace elements are indispensable but in larger concentrations many of them, such as copper, arc highly toxic.