This Vitamin & Mineral Table was taken from "Vitamin and Mineral Pyramid" by Aquarium Pharmaceutical, Inc. - Technical Reference Sheet.
To prevent these deficiencies, use a food which contains proper levels of these elements. This will promote a healthy and proper balance of supplements to maintain and sustain all freshwater fish.
Vitamin and Mineral Deficiencies and the impact on Fish Health:
Vitamin A - Impaired growth, body depigmentation, pop eye, accumulated body fluids.
Vitamin D3 - Poor growth, impaired calcium balance.
Vitamin E - Reduced survival, poor growth, anaemia, increased water retention.
Vitamin C - Scoliosis, deformative growth, hemorrhagic skin, liver, kidney, intestine and muscle.
Riboflavin - Cloudy eyes, hemorrhagic eyes, dark body coloration, poor appetite, poor growth.
Niacin - Loss of appetite, jerky or difficult motion, weakness, muscle spasms, poor growth.
Menadione - Prolonged blood clotting, anaemia.
D-pantothenic - Loss of appetite, clubbed gills, gill exudate, sluggishness, poor growth.
Folic Acid - Poor growth, lethargy, dark skin coloration, fragile caudal (tail) fin.
Pyridoxine - nervous disorders, hyperirritability, loss of appetite, rapid and gasping breathing.
Thiamine - Poor appetite, convulsions, instability and loss of equilibrium, muscle deformation.
Biotin - Loss of appetite, spastic convulsions, skin lesions, poor growth.
Vitamin B12 - Poor appetite, anaemia.
Calcium - Reduced growth.
Manganese - Reduced growth, loss of equilibrium, dwarfism, high mortality.
Zinc - Reduced growth, anorexia, fin and skin erosion, reduced bone calcium.
Iodine - Thyroid hyperplasia (abdominal increase of thyroid cell growth).
Copper - Reduced growth, lack of important metabolic enzymes.
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Do Discus Pairs Really Form Secretions? By Horst W. Koehler “Diskus Brief” Sept. 1989 Translated by Paul Ceroke, Urbaira; reprinted in “Our Discus” N.A.D.S. Volume 4 Issue 2, 1990.
If everything is proceeding normally, the discus brood will, after their three to four day yolk sac phase, begin moving towards the sides of their parent’s bodies along the shortest route possible. The free swimming fry frequently concentrate themselves on the upper half of the body, especially around the base of the dorsal fin. The common belief is that the adult fish which alternate in leading the young fry, produce a secretion (“Discus milk”) upon which the young feed and which serves as their first food.
Two scientists from the DDR have now explained what the young fry are really taking in. To explain this interesting function, examinations were conducted on; the brooding parent fish as well as on sexually inactive discus fish, and also on the stomach contents of the larval discus fish.
Morphology of Fish Skin
To be able to properly understand and interpret the results of the examination, a basic introduction to the skin, which is the body covering of all fish, is presented here. The fish skin is composed of two separate layers; the external surface (epidermis), and the inner underlying skin (corium). Still further inwards is the tissue underlying the skin (sub cutis or hypodermis), and finally the body muscles. The last are composed of the cross banded muscle tissue, as well as their supplying capillaries and the nerves.
In the underlying skin of the discus, as is the case with most fish, the very small scales are anchored. Together with the stable underlying skin layer, they “armour” the fish and protect it from mechanical and other damage. The epidermis is composed of many cells arrayed over each other, the multi-layered epithelium. All layers arise from the lowest layer of cells, basal cell layer. Many varied glandular cells are in the epidermis. Some of these, the ellipsoidal, cup-shaped slime cells, discharge their secretion outwards. It disperses over the surface of the epidermis and makes it smooth and slippery. This slime layer is continually renewed; it protects the skin from colonization by fungi and bacteria, and it is also effective in restricting inflammation. Slime production by the cup-shaped cells is probably so retarded by the presence of toxic substances in the aquarium water, that it can resemble the symptoms of fresh water allergy; admittedly, the validity of this close connection still remains unexplained as it was before.
Additionally, in the underlying skin layer beneath the scales, there occurs yet another unique characteristic of the skin; the dye cells called chromatophores. They contain very small pigmented bodies and they are responsible for the colouration and patterns of the fish. It is understandable that, during chemical damage to the skin (too high or too low a pH, fresh water allergy), the function of the chromatophores is also impaired so that the afflicted discus fish appear dark to black.
Changes in the Skin of Brood Rearing Discus Fish
In their examinations, Dr. Heinz Bremer and DR. Ulrich Walter have determined the following changes in the anatomy and histology of the skin in brood rearing discus cichlids. Additionally, the histological and surface chemical examinations of the DDR scientists have shown that the epidermal structure of brood rearing and sexually immature or inactive discus fish are in principle, qualitatively identical. Quantitatively of course, there exist considerable differences. Among fish which are not in the brood rearing period, the area of the epidermis close to the body has a distribution of cells that has shown to be isolated; only the outer layer of skin, a flat epithelium, is comprised of two to three layers of cells. The large number of specially formed cells, however, the so called sekretoblasten, and their “ripening” to glandular cellular elements, the so called “sekretocyten” scarcely occurs among sexually inactive fish.
Probably these glandular cellular elements are a previously unknown type of cell, whose occurrence is restricted to the discus.
How do these cells change in the brood rearing fish? What develops from this is that in brood rearing discus fish, in the body area of the epidermis, a high rate of cellular division occurs. On the surface of the skin, the epithelium is arranged in layers of very flat cells, 8 to 11 lamella. No further division process occurs in the flat upper layer of the discus brood. This cellular material is a component of the food which the discus fry take up from their parents.
The second component of the food arises in the basal layer of cells. As already described above, the formation of sekretoblasten cells occurs. While these, however, scarcely ever develop any further in non-brood rearing discus they “ripen” into the so called sekretocyten in brood rearing discus fish. In the course of the ripening process, these cells migrate to the outer layer of the skin to “burst” or extrude”. These sekretocyten are by no means genuine glandular cells, since the natural release of the cellular contents (vacuole contents) does not take place on the epidermis. The sekretocyten are like-wise taken in by the discus fry. It can be explicitly demonstrated that no roll is played by the actual slime cells which are present on the skin of all fish.
Examinations of the Stomach contents of Discus Fry
The stomach contents of the larvae, that is the day old discus fish, confirm without a doubt that no slime is taken in from the skin, but rather – as mentioned above – epidermal material and sekretocyten. What is impressive is the low concentration of carbohydrate and lipids in these sekretocyten; in this way, overloading of the digestive tract of newly free swimming fish whose digestive glands are not capable of delivering digestive enzymes to the stomach is prevented.
In the stomach of the fry, aside from epithelial bacteria (which can also be found on the epidermis of the adult fish), gravel algae can also be found. Presumably this intake of bacteria accelerates the development of the physiologically important intestinal flora.
The Results of the Research Summarized above allow the following Conclusions:
1. A secretion as a discharge product of cells which have produced it, does not exist in discus fish. The protective slime layer which exists in every fish, likewise plays no role in the feeding of larval discus. The story often circulated among discus aquarists how “discus milk” is suckled is not applicable.
2. During the reproductive period of the parent discus, there occurs a hormonally controlled Hypertrophierung (enlargement through cellular growth) of the skin.
3. The results described also make it clear that discus fish are especially sensitive to various pollutants in their environment (first in importance is the water itself, but also the air).
4. The skin particles taken in by the fry have not only nutritional function.
5. There are no significant differences between the sexes among brood rearing discus parents.
Abbildung:
The various layers of the fish skin after the Epidermis and the Corium in the pockets of which the very small scales of the discus lie, and which forms the actual skin (cutis). Further inwards (inwards toward the body) are the underlying tissue and the skeletal musculature.
Literature:
1. Bremer, H. and Walter U: Histologische, ultrastrukturelle and topochemische Untersuchungen zur Brutpflege von Symphysodon aequifasciatus Pellegrin 1903. Gegenbaurs morph. Jahrbuch Leipzig 132 (1986)2,S. 183-194.
2. Bremer, H. and Walter, U.: Wasfressen junge Diskusbuntbarsche? Aquarien-Terrarien 1/1986,S. 14-17.
3. Sterba, G.: Aquarienkunde. Verlag Eugen Ulmer, Stuttgart, 1989 (Lizenzausgabe).
4. Schriftliche Mitteilungen von Dr. Heinz Bremer and den Verfasser vorn 12.11.86 und 7.1.87.
