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The underwater

In this issue: • Aquaculture needs algae • Can fish be vaccinated against white spot? • Aquarium fish feeding

A collection of articles for the home aquarium enthusiast


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Contents 4

Aquaculture needs algae

Mr Frederic Barrows, a lead scientist for the USDA’s agricultural research says that “Over the last 20 years the yield of fish meal has been pretty much constant, so we aren’t getting any more fish feed out of the ocean and we aren’t getting any more fish meal ingredients.” This means that too many fish have been used in the past, so now an alternative is needed. 6

Can fish be vaccinated against white spot?

There are a number of different treatments already available for white spot, or “ich”, but none of them can cure or prevent the disease amongst fish. 8

Aquarium fish feeding

Aquarium fish hobbyists can enjoy an impressive range of species, whose number is increasing every year.

Produced & Edited by: Emily Stables Published by: Perendale Publishers Ltd 7 St George’s Terrace, St James’ Square Cheltenham, Glos, GL50 3PT United Kingdom Tel: +44 1242 267700 Fax: +44 1242 267701 info@perendale.co.uk www.perendale.com All data is published in good faith, based on information received, and while every care is taken to prevent inaccuracies, the publishers accept no liability for any errors or omissions or for the consequences of action taken on the basis of information published. Copyright 2011 Perendale Publishers Ltd. All rights reserved. No part of this publication may be reproduced in any form or by any means without prior permission of the copyright owner.

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ISSN No: 1466-3872


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Aquaculture needs algae

r Frederic Barrows, a lead scientist for the USDA’s agricultural research says that “Over the last 20 years the yield of fish meal has been pretty much constant, so we aren’t getting any more fish feed out of the ocean and we aren’t getting any more fish meal ingredients.” This means that too many fish have been used in the past, so now an alternative is needed. Fish meals next key nutritional ingredient is Algae. Nearly every species of fish uses it already, including various warm and cold water varieties. Mr Barrows explained, “All types of species in aquaculture are interested in the essential fatty acids that can be found in algae because that is what makes fish a heart-healthy, brainhealthy, food,” meaning algae can provide just as many nutrients to the fish as the smaller fish can.

The algae diet Certain species of fish benefited immensely from the algae diet. White sea bass and rainbow trout are two examples of species that performed better on an algae diet instead of a fishmeal diet.

“I had to repeat this three times before I had the courage to say we outperformed the commercial diet,” Barrows said, “because I’m usually happy if we can match the commercial diets.” However, the increased algae diet caused a 70 percent increase in the mortality rate of fish. Mr Barrows said

“I had to repeat this three times before I had the courage to say we outperformed the commercial diet,”

“This can be attributed to either a missing nutrient or the increased feed intake by the fish. Neither is a breaking point, as diets can be adjusted to compensate for such occurrences.”

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Can fish be vaccinated against white spot?

T

here are a number of different treatments already available for white spot, or “ich”, but none of them can cure or prevent the disease amongst fish. Chemicals are usually added to the water to treat white spot, but there are problems that come with using them, such as they can be expensive and they can also disrupt and harm the fish in the aquarium. Another treatment commonly used to remove white spot once it occurs is Malachite green. However this treatment has been banned on many fish farms because it is known to cause cancer in humans.

Immunity to white spot Scientists have discovered that fish can develop immunity to white spot following an infection. Experiments have been conducted to test to see whether vaccines can be developed from giving fish immunity.

“Scientists have discovered that fish can develop immunity to white spot following an infection” The vaccine that has been developed for white spot so far consists of putting fish in water filled with parasites. The parasites, however are at a stage in their life where they are known as “Theoronts.” Theoronts have been proved by scientists to decrease a fishes’ chance of developing white spot. This is because the parasites cause the fish to produce antibodies in their bloodstream, which can also help them to fend off other diseases and illnesses as well as white spot. This method however, is still being tested and is not yet finalised.

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“Chemicals can be expensive and they can also disrupt and harm the fish in the aquarium�

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Aquarium fish feeding

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by Aleksandra Kwaśniak-Placheta, * and Leszek Moscicki** *Tropical - Tadeusz Ogrodnik, 25 Opolska Street, 41-507 Chorzow, Poland; **Lublin University of Life Sciences, 44 Doświadczalna Street, 20-280 Lublin, Poland

quarium fish hobbyists can enjoy an impressive range of species, whose number is increasing every year. In response to the growing aquarists’ needs manufacturers introduce foods with more and more sophisticated formulas. However, data concerning dietary habits of wild specimens are rudimentary and extremely hard to obtain. The knowledge about fish’s needs comes from observation rather than rigorous research.

Therefore, the common practice is to use research carried out on fish for human consumption instead despite the fact that it is not possible to create and maintain natural network of feeding relations in aquarium and many species-typical behavior patterns are simply not observed. No wonder that a diet of aquarium fish is becoming more universal. In the wild fish feed on insects, molluscs, crustaceans, fish, plants, algae, etc.

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These foods differ in terms of quality and quantity of nutrients. In addition, fish’s diets vary throughout the year, as food availability varies depending on the season. In the absence of their primary food, fish are forced to resort to less palatable alternatives, which they have declined so far. It’s not possible to imitate natural living conditions of wild fish but you can compose a diet based on products with nutrient-rich compositions to diversify their diet, hence prevent

nutritional deficiencies and numerous medical disorders. The most vulnerable is the hatch. Any deficiencies it experiences during this period can lead to deformities and developmental disorders. For instance, Artemia nauplii, commonly used for rearing fry, lead to the decalcification of bones and reduction of the survival rate, if not supplemented by other foods.

Nutritional requirements In terms of their nutritional

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requirements ornamental fish can be divided into herbivores, omnivores and carnivores. Prepared foods for herbivorous fish should be characterised with high content of plant material, including spirulina, chlorella, Kelp algae, spinach, nettle, etc. They should also be fed with fresh or frozen plants, mostly spinach, broccoli, zucchini, carrots, etc. For carnivorous fish, which in the wild feed on fish, roe, fry and invertebrates, there’s a choice of frozen foods (krill, shrimps, fish fillets, squid, Daphnia pulex, Artemia, bloodworms, Tubifex etc.) and live foods (fish, Daphnia, Artemia, bloodworms, Tubifex, glassworm etc.) and multi-ingredient and high-protein prepared foods.

Prepared foods for aquarium fish Prepared foods available on the pet market can be divided into: multiingredient universal foods, used in feeding of most popular aquarium fish species and specialist foods, dedicated to particular species or groups of fish with sophisticated dietary demands, such as Tropheus cichlids, Malawi cichlids of mbuna group which feed on periphyton, breeding discus, goldfish, red parrots and algae-eaters from Loricariidae family etc. A special group of foods are products enriched with various natural resources that improve fish’s health, enhance their coloration and increase their resistance to diseases. The diversity of formulas is

accompanied by a variety of forms in which prepared foods are available, so you can choose product perfectly adjusted to the size of your fish’s mouth and their way of feeding (from the surface of the water, its middle layers or from the bottom - see Figure 1). The best feeding solution for bottomfeeders are granules and tablets. Fish feeding in the middle layers of the tank or at the bottom prefer slowly sinking granules, which turn out particularly effective in multi-species tanks with fish eating in various parts of the aquarium. Fish with small mouth eating under the surface of water will choose flakes, which prove highly effective in tanks where intraspecific competition takes place and weaker fish have a limited access to food. Flakes, floating all over the tank, are easily accessible even for smaller and weaker fish. Tablets are recommended for timid fish, as they can be placed in fish’s favourite hiding places and for feeding the fry, due to the small particles that make up the tablet.

Immunity enhancing components Prevention in fish is more effective than medical treatment. Well-nourished fish with a strong natural resistance to diseases is more likely to cope with stress (transport from farms to wholesalers, store, the customer’s home) and pathogens. In prepared foods for ornamental fish one can find

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numerous substances and resources, whose components enhance the immune system, for example stabilised vitamin C, beta-glucan, unsaturated fatty acids, spirulina, Kelp algae, chlorella, etc. Stabilised vitamin C is a L-ascorbyl2-polyphosphate resistant to high temperatures. Vitamin C reduces stress, stimulates the immune system, strengthens blood vessel’s walls and accelerates wound healing. Unsaturated fatty acids (UFAs), including long-chain fatty acids Omega-3 and Omega-6, accelerate the regeneration of tissues, including skin, improving its function as a protective barrier. Moreover, they are a building material of hormone-like cellular messengers prostaglandins and reproductive cells. Part of the demand for Omega-3 and Omega-6 fish cover themselves by producing them from simple UFAs, which they obtain from food. However, carnivorous and marine fish should be supplied with Omega-3 fatty acids, because their ability to process them from simple UFAs is small. Beta-1.3/1.6-glucan - a polysaccharide derived from yeast’s cell walls - is a natural immune stimulator that directly affects macrophages, increasing their capacity for phagocytosis of alien cells and their own cancer cells. Extremely valuable components of foods for aquarium fish are algae and spirulina (Arthrospira platensis). The share of the latter in fish feed

depends on, inter alia, a very high protein content (55-70 percent) characterised by a high digestibility (90 percent). In addition, protein of Spirulina contains most essential amino acids for fish (if not all). The cell’s walls of this cyanobacterium are composed of mucopolysaccharides, which act as immunostimulators. In the cells of spirulina one should find three times more chlorophyll than in plants. Chlorophyll reduces the number of putrefactive bacteria in the gastrointestinal tract. The high content of carotenoids, especially betacarotene, makes foods with spirulina intensify coloration in fish, which is essential in case of colourful breeding forms. Thanks to so many different substances spirulina enhances vitality and encourages the immune system. Other relatively common algae supplements of aquafeed are chlorella and Kelp algae. Chlorella is known for its high concentration of chlorophyll (seven percent in the dry matter) and large protein content (50 percent in the dry matter), rich in essential amino acids. Health benefits are attributed to Chlorella Growth Factor, rich in nucleic acids. Kelp algae is a mixture of marine seaweed belonging to the brown algae, which are rich in minerals, including well-assimilable organic iodine compounds, UFAs, and vitamins. Their addition has a beneficial effect on metabolism and general condition of the fish.

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Herbs in the aquarium Not only have the herbs been applied to treat people, they are also commonly used as a dietary supplement in feeds for livestock and domestic pets. Herbs enhance food palatability, stimulate animals’ appetite, aid digestion and improve overall health. They also act as an anti-inflammatory, antidiarrheal and bacteriostatic agents. Herbs are also present in the aquarium. They play an important role in the preparation of water and are used as a component of both prepared foods and those produced in house conditions. In Europe there are 25 species of basic herbal raw materials, including garlic and common nettle, which are used in foods for ornamental fish. To manufacture prepared food producers also use plants rich in the so called fitamins, which act on the body in a manner similar to vitamins. But unlike the vitamins, they do not have to be delivered each day. Fitamins are present in vegetable and herbal plants. They regulate metabolic processes, detoxicate body and enhance overall condition. Fitamins include among others: polyphenols (flavonoids and phenolic acids), sulfur compounds (such as allin in garlic), tannins and carotenoids. The exceptional sources of fitamins in foods for fish are garlic, spinach, spirulina and Kelp algae. Garlic (Allium sativum) is a well-known spice and herbal plant. Its cloves are composed of sulphur-containing compounds, inter alia, allin which

becomes allicin when garlic is crushed. This is allicin to which garlic owes its strong antiseptic properties and its characteristic flavour. Garlic also contains flavonoids, pectins, mucilages, several vitamins and trace elements. Before it started to be widely used in prepared foods for fish, it had been added by fish enthusiasts to mixtures they had prepared in their homes, especially the ones for the discus, often targeted by gastrointestinal parasites. Foods for ornamental fish also utilise nettle (Urtica dioica). The active substances in this plant are organic acids, flavonoids, carotenoids, tannins and others. Thanks to them, nettle regulates digestion. As a food supplement it has a beneficial influence on digestion and provides a number of fitamins, vitamins and trace elements.

Invertebrates used in feeding of ornamental fish Before fish enthusiasts could take advantage of convenient and easy-tostore prepared foods, they had had to use natural foods, which they fished or bred themselves. Despite many advantages the use of living organisms in the aquarium has one fundamental flaw – the organisms derived from nature can be a source of dangerous pathogens. To avoid this threat you can chose frozen, dried and freeze-dried products. Invertebrates have also become the essential ingredient of prepared foods (see Table 1).

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Antarctic Krill (Euphausia superba) is a source of easily-digestible protein, rich in essential amino acids. It is readily consumed by fish, especially in its processed form as an additive in flakes, granules and tablets. It is also characterized by a high palatability, resulting from the presence of amino acids (glycine, proline), nucleic acids and TMAO (trimethylamine oxide). These substances affect the taste and smell of the food. This is of particular importance in case

“It is much more complicated than the production of aquafeed for fish farming”

unsaturated fatty acids (approximately 14 percent) and high content of saturated fatty acids (approximately 28 percent of palmitic acid) the food cannot be used too often, because it can cause fatty degenerations and deficiency of PUFAs. Due to its high protein content it is a perfect food for spawners and fish weakened by illness or long transport, especially that fish take it very eagerly. Tubifex (Tubifex tubifex) lives in bottom sediments, where they feed on organic matter, algae and bacteria that live in them. These organisms are very resistant to various pollutants that can accumulate in them. However, using Tubifex from polluted environment can lead to poisoning of fish. Tubifex and chironomids are both added to prepared foods and subjected to freeze-drying process. Daphnia is a source of protein and fat (including UFAs).

of feeding wild caught specimens and commercial farming fish, which aren’t used to eat prepared foods and need encouragement. Apart from valuable protein Krill provides fish with unsaturated fatty acids, out of which 40 percent are PUFAs (polyunsaturated fatty acids), including 14.7 percent EPA and 8.3 percent DHA. Krill is also a great source of carotenoids ‒ natural pigments that enhance fish’s coloration. Chironomids – red mosquito larvae – constitute a high-protein food, which contains around 60 percent crude protein and 10 percent fat in the dry matter. Due to the low content of

However, it contains a small number of highly unsaturated fatty acids: EPA and DHA. Protein content (20-25 percent) and fat content (2.4-20 percent) vary widely depending on the feed base of the tank, where crustaceans live and on the season. The composition of Daphnia resembles freshwater shrimp: Gammarus pulex, which contains similar amount of valuable protein. It is a good source of unsaturated fatty acids, including n-3 acids, and carotenoids. One kilogram of dry matter of Gammarus pulex contains about 700-800mg of carotenoids (with astaxanthin share of 40 percent).

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Artemia salina (Artemia sp.) is a popular food for ornamental fish. It is used in its larval form (also independently hatched in house conditions), frozen or freeze-dried adult forms, or as an additive to prepared foods. Newly hatched larvae of Artemia contain 89 percent water, 6.7 percent crude protein, 2.1 percent fat, 1.1 percent ash and after drying ‒ 58 percent protein, 20 percent fat and 10 percent ash. Adult Artemia contains 60 percent protein, 13 percent fat and 12 percent ash in the dry matter.

take into account the proportions of multi-ingredient, vegetable and highprotein foods in the diagrams shown on Figure 3.

Conclusive remarks Manufacture of aquaristic feeds which meet high quality standards require an extensive know-how, the accuracy of processing and the use of a modern and sophisticated technological equipment. It is much more complicated than the production of aquafeed for fish farming.

The quality of aquarium foods is immediately visible after the application, in the literal sense. Aquarist will immediately notice the loss of every single fish or the contamination of water in the tank caused by the dust Table 1: The content of crude protein, crude fat and ash in from crumbled selected aquatic invertebrates food, quickly (% of the dry matter) decaying wastes or colorants. Raw material Crude protein Crude fat Ash Despite the wide When composing a diet for your fish, follow the basic nutritional principles, taking into account the nutritional value of main nutrients. Compacted

range of various foods on the market, only few 10.4 12.6 of the offered products meet the 10.0 11.0 highest nutritional 2.4 19.0 criteria, can 20.1 4.5 guarantee safety of feeding and do not contaminate the aquatic environment.

Artemia - adult form

60.0

13.0

12.0

Artemia larvae - nauplii

58.0

20.0

10.0

krill

70.0

Chironomidae

60.0

Daphnia

50.0

Tubifex

47.8

information concerning this issue is shown in Figures 2 and 3.

When composing a diet for your fish,

The form and functionality of the packaging units are equally important.

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The expectations of the customers in this aspect are justifiably high as the options are impressive: containers acting as feeders, helping keep food in sterile conditions, transparent, but at the same time protected from ultraviolet radiation (see Figure 4). These challenges can be met only by few companies.

Literature Bernard J.B., (1997), Feeding captive insectivorous animals: nutritional aspects of insects as food, Nutrition Advisory Group Handbook, Fact Sheet 003; Ciferri O., (1983), Spirulina, the edible microorganism, Microbiological Reviews, December, 551-578; Clifford Chan, (2003), Exotic Discus

of the World, Clean Ace Printing Press, Singapur; Floreto E.A.T; Brown P.B.; Bayer R.C., (2001), The efects of krill hydrolysatesupplemented soya-bean based diets on the growth, colouration, amino and fatty acid profiles.; Aquaculture Nutrition 7; 33-43; Gaillard M. et al., (2004), Carotenoids of two freshwater amphipod species (Gammarus pulex and G. roeseli) and their common acanthocephalan parasite Polymorphus minutus, Comparative Biochemistry and Physiology, Part B 139,129–136; Ghioni C., Bell J.G., Sargent J.R., (1996), Polyunsaturated Fatty Acids in Neutral Lipids and Phospholipids of Some Freshwater Insects, Comp. Biochem. Physiol. Vol. l14B, No. 2, pp. 161-170; Hasik J., (2001), Usprawnienia dietetyczne

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procesów metabolicznych. Co to są fitaminy?, (in Polish), Postępy Fitoterapii nr 6, (2-3); Kibria G. et al., (1999), Utilization of wastewater-grown zooplankton: Nutritional quality of zooplankton and performance of silver perch Bidyanus fed on wastewater-grown zooplankton, Aquaculture Nutrition 5, 221-227; Lutomski J., (2001), Znaczenie ziół w terapii i dietetyce (in Polish), Postępy Fitoterapii 6, 2-3; Opuszyński K., (1979), Podstawy biologii ryb (in Polish), PWR i L, Warszawa; Sushchik N.N. et al., (2003), Comparison of fatty acid composition in major lipid classes of the dominant benthic invertebrates of the Yenisei river, Comparative Biochemistry and Physiology Part B 134, 111–122; Tacon A.G.J., (1987), The nutrition and feeding of farmed fish and shrimp - a training manual 2. Nutrient sources and composition, A report prepared for the FAO Trust Fund GCP/RLA/075/ ITA Project Support to the Regional Aquaculture Activities for Latin America and the Caribbean, Food And Agriculture Organization Of The United Nations, Brazil;

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