Transition metals are essential for health, forming integral components of proteins involved in all aspects of biological function. However, in excess these metals are potentially toxic, and to maintain metal homeostasis organisms must tightly coordinate metal acquisition and excretion. The diet is the main source for essential metals, but in aquatic organisms an alternative uptake route is available from the water. This review will assess physiological, pharmacological and recent molecular evidence to outline possible uptake pathways in the gills and intestine of teleost fish involved in the acquisition of three of the most abundant transition metals necessary for life; iron, copper, and zinc.

P. Carriquiriborde (from the Environmental Research Centre, National University of La Plata-CONICET, La Plata, Argentina), R. D. Handy, and S. J. Davies (School of Biological Sciences, University of Plymouth, UK), have published a report entitled: Physiological modulation of iron metabolism in rainbow trout (Oncorhynchus mykiss) fed low and high iron diets. From the abstract:

Iron (Fe) is an essential element, but Fe metabolism is poorly described in fish and the role of ferrireductase and transferrin in iron regulation by teleosts is unknown. The aim of the present study was to provide an overview of the strategy for Fe handling in rainbow trout, Oncorhynchus mykiss.

J. Burke and R. D. Handy (again, from the School of Biological Sciences, University of Plymouth, UK), have published a report entitled: Sodium-sensitive and -insensitive copper accumulation by isolated intestinal cells of rainbow trout Oncorhynchus mykiss. From the abstract:

The pathway for copper (Cu) uptake across the mucosal membrane into intestinal cells has not been elucidated in fish. Copper accumulation in freshly isolated intestinal cells from rainbow trout Oncorhynchus mykiss was measured after exposure to 0–800 µmol l^–1 CuSO₄ for 15 min.

Update (Dec 2010) – sadly, the Native Fish Conservancy seems to have met an untimely end. The above link is via the Internet Archive. If any of the former webmaster/site managers are out there please feel free to make contact.

From the introduction:

This work is meant to provide a guide to the freshwater fishes of Iran. There are no modern keys to this fauna, some available books are incomplete or cursory treatments or outdated, and the detailed and diverse scientific literature is widely scattered in time, languages and journals. Iran lies at a region of major zoogeographical interchange and has a diverse and interesting ichthyofauna about which comparatively little is known. An accurate identification is a pre-requisite for further scientific studies and this website aims to serve that purpose and to be an introductory guide to the fishes. The guide is aimed at a mixed audience, including scientists familiar with ichthyology to whom some introductory sections of this work will be superfluous, and those whose knowledge of fishes is embryonic or who may have limited access to literature sources.

This work has been carried out over a period of over 30 years from my first arrival in Iran in January 1976. In that year, 7 articles were published strictly on Iranian fishes (3 on parasites, 1 on pesticides, 1 on fisheries, 1 describing the blind white fish and 1 a summary of the latter; 2 were in Farsi). In 2006, 160 articles on Iranian fishes appeared, along with many relevant works from neighbouring countries, works on the aquatic environment in Iran and works on taxonomy and systematics relevant to Iran. The study of fishes is now a very active field within Iran and the Middle East. Accordingly, 2006 is the last year that this work was updated although some systematic and taxonomic studies may still be incorporated.

…leading expert on VHS in the United States, Jim Winton of the US Geological Survey, indicated that the VHS virus exists in four strains, with a single, unique sub-strain occurring in the Great Lakes. The VHS virus has been known in Europe, Japan, and the coasts of the U.S. for many years; how it came to occur in the Great Lakes is not known. Winton speculates that it may have originated in ballast water from ocean-going ships sailing into the Great Lakes, or that it may have hitchhiked in shipments of hatchery-raised fish.

According to the New York State Department of Environmental Conservation (NYSDEC),

Viral hemorrhagic septicemia (VHS) virus is a serious pathogen of fresh and saltwater fish that is causing an emerging disease in the Great Lakes region of the United States and Canada. VHS virus is a rhabdovirus (rod shaped virus) that affects fish of all size and age ranges. It does not pose any threat to human health. VHS can cause hemorrhaging of fish tissue, including internal organs, and can cause the death of infected fish. Once a fish is infected with VHS, there is no known cure. Not all infected fish develop the disease, but they can carry and spread the disease to other fish. VHS has been blamed for fish kills in Lake Huron, Lake St. Clair (MI), Lake Erie, Lake Ontario, the St. Lawrence River and Conesus Lake (Western NY). The World Organization of Animal Health has categorized VHS as a transmissible disease with the potential for profound socio-economic consequences. Because of this, they list VHS as a disease that should be reported to the international community as an exceptional epidemiological (study of diseases in large populations) occurrence.

The NYSDEC has released revised Emergency Regulations Adopted to Prevent Spread of VHS.

Animal and Plant Health Inspection Service (APHIS) note the following species are susceptable: Atlantic cod Gadus morhua, Black crappie Pomoxis nigromaculatus, Bluegill Lepomis macrochirus, Bluntnose minnow Pimephales notatus, Brown bullhead Ictalurus nebulosus, Brown trout Salmo trutta, Burbot Lota lota, Channel catfish Ictalurus punctatus, Chinook salmon Oncorhynchus tshawytscha, Coho salmon Oncorhynchus kisutch, Chum salmon Oncorhynchus keta, Emerald shiner Notropis atherinoides, Freshwater drum Aplodinotus grunniens, Gizzard shad Dorosoma cepedianum, Grayling Thymallus thymallus, Haddock Gadus aeglefinus, Herring Clupea spp, Japanese flounder Paralichthys olivaceus, Largemouth bass Micropterus salmoides, Muskellunge Esox masquinongy, Pacific cod Gadus macrocephalus, Pike Esox lucius, Pink salmon Onchorhynchus gorbuscha, Pumpkinseed Lepomis gibbosus, Rainbow trout Oncorhynchus mykiss, Redhorse sucker Moxostoma spp, Rock bass Ambloplites rupestris, Rockling Onos mustelus, Round goby Neogobius melanostomus, Smallmouth bass Micropterus dolomieu, Sprat Sprattus spp, Turbot Scophthalmus maximus, Walleye Sander vitreus, White bass Morone chrysops, White perch Morone americana, Whitefish Coregonus spp, Yellow perch Perca flavescens.

APHIS has also released the Amended Federal Order Viral Hemorrhagic Septicemia (VHS) dated May 4, 2007. The purpose of this Federal Order is to prevent the spread of viral hemorrhagic septicemia (VHS) into aquaculture facilities. Also refer to the APHIS July 2006 Emerging Disease Notice – Viral Hemorrhagic Septicemia in the Great Lakes for further analysis.

Research reports published from the Scottish Fisheries Research Services may serve to provide management options:
Viral Haemorrhagic Septicaemia (VHS) – from the abstract:

Viral haemorrhagic septicaemia (VHS) was diagnosed inrainbow trout (Oncorhynchus mykiss) at a farm in Englandon 26 May 2006. VHS is a notifiable disease in the UK and a List II disease under European Directive 91/67/EEC. Investigations into the source and potential spread of the disease are being carried out by Centre for Environment, Fisheries and Aquaculture Science (Cefas) in England and Wales, and by Fisheries Research Services (FRS) in Scotland. VHS has occurred once before in the UK, in 1994, affecting a single turbot farm. The disease was successfully eradicated on that occasion. VHS has no implications for human health.

Risks to Wild Freshwater Fisheries from Viral Haemorrhagic Septicaemia (VHS) – from the abstract:

There is a risk of transfer of VHSV from farmed to wild freshwater fish species and vice versa. There is evidence that a reservoir of infection may be created in wild freshwater fish species. This may pose a risk of re-infection of farms (eg rainbow trout). There are no reports of VHSV infection leading to significant disease outbreaks in wild freshwater fish stocks. Based on evidence from outbreaks in farms and experimental evidence, free living rainbow trout, brown trout, whitefish, grayling and pike may be at risk of disease. Available evidence suggests a high infection pressure would be required to initiate a disease outbreak in wild fish (eg shedding of virus from an infected farm).

Disinfection guide version IV: practical steps to prevent the introduction and minimise transmission of diseases of fish – from the abstract:

Emerging diseases have had a significant impact on development of the Scottish aquaculture industry, highlighting the importance of preventing their introduction and minimising their transmission. The risk of disease spread is reduced by the implementation of good sanitary practices by fish farmers, and fisheries and the application of effluent disinfection systems in the processing industry. To maintain healthy fish stocks and minimise the introduction and spread of disease, the aquaculture industry should ensure best practice on farm sites, during transportation of live or dead fish and equipment, at the processing plant and during subsequent effluent and waste disposal. For an assessment of the risks associated with specific tasks, reference should be made to the Final Report of the Joint Government/ Industry Working Group on Infectious Salmon Anaemia (ISA) available from the Fisheries Research Services (FRS) web site, at www.frs-scotland.gov.uk. The protocols described in this guide are based upon current scientific knowledge and practical experience and will continue to be developed as the needs of industry change. This guide is intended for distribution to relevant industry personnel.

Kenneth Williams and Glen Gebhart have published a report entitled Controlling Aquatic Vegetation with Grass Carp. From the introduction:

Excess aquatic vegetation causes problems in both aquaculture ponds and in farm ponds used for either sport or food fish production. The main problems caused by rooted and filamentous aquatic vegetation in aquaculture ponds are: interference with fish harvest operations, use of nutrients that could be more efficiently utilized by phytoplankton for dissolved oxygen production, reduction of water circulation that increases stratification and lowers dissolved oxygen levels. Excess aquatic vegetation in farm ponds interferes with hook and line harvest and increases the possibility of overpopulated, stunted forage fish populations, and reduces the aesthetic value of the pond for swimming and recreation. Grass carp are used to great advantage in both situations.

Grass carp do not breed easily in ponds, in their natural environment preferring swift moving water. Kenneth Williams, again, has published information on Grass Carp Propagation. From the introduction:

Spawning does not occur in ponds and lakes. Reproductive organs reach an incomplete state of development and become dormant. As water temperature rises above 80 degrees F. eggs and milt are resorbed into the fish.

Natural spawning conditions do not exist for grass carp in the United States with the possible exception of the Mississippi river. Successful grass carp spawning and hatching requires a thorough knowledge of the fish, healthy brood stock, gentle handling and an understanding of induced hormonal spawning techniques.

Michael P. Masser has published a document July 2002, entitled Using Grass Carp in Aquaculture and Private Impoundments. From the abstract:

The U.S. Fish and Wildlife Service, in cooperation with Auburn University, first introduced grass carp into the U.S. in 1963 to investigate their usefulness in controlling aquatic vegetation. No native North American species of fish is as strictly herbivorous as the grass carp. Therefore, there are no native species available for aquatic vegetation management. Grass carp have proven to be effective in controlling many species of algae and submerged aquatic vegetation.

Larry Sanders, Jan Jeffrey Hoover, and K. Jack Killgore have published a 1991 report entitled Triploid Grass Carp as a Biological Control of Aquatic Vegetation. Triploid grass carp are sterile, thus eliminating the concern of the species forming sustainable, breeding populations. The article reviews

the development and biology of the triploid grass carp and provides recommendations for its use as a biological control of nuisance aquatic vegetation. Triploid and diploid grass carp are morphologically identical and, reproduction notwithstanding, are assumed ecologically similar. Therefore, most data obtained from studies of diploid fish should be applicable to triploid fish.

Aquaculture CRSP report on the Polyculture of Grass Carp and Nile Tilapia with Napier Grass as the Sole Nutrient Input in the Subtropical Climate of Nepal. The objectives of the research:
1) Evaluate the growth of grass carp and tilapia fed with napier grass in polyculture.
2) Evaluate the nutrient and water quality regimes of pond water.
3) Determine the composition of foods consumed by Nile tilapia.
4) Determine the optimal ratio of grass carp to Nile tilapia in polyculture.

The FAO have published a summary of grass carp culture entitled Cultured Aquatic Species Information Programme Ctenopharyngodon idella. As part of a section on status and trends, they observe:

Grass carp not only grow quickly but have a low requirement for dietary protein. They can be produced at low cost by feeding them with aquatic weeds, terrestrial grasses and by-products from grain processing and vegetable oil extraction. Seed can be produced through induced breeding at a large scale and very low cost. The culture of grass carp can be well integrated into crop farming and animal husbandry, to maximize the utilization of natural resources. On the other hand, it is a large fish without fine inter-muscular bones. It is acceptable to consumers in many countries and it very likely has good potential for development. The market for grass carp is close to saturation in the eastern part of China, where aquaculture is well developed now. However, there is still a considerable potential market in central and western China and many other developing countries.

The number of trout 12 inches and longer sold during 2005 totaled 55.5 million fish, up 12 percent from the previous year. The average price per pound was $1.05, up 2 cents from 2004. The value of sales for the 2005 marketing year was 62.6 million dollars, up 5 percent from 2004. Based on the dollar value, 67 percent were sold to processors and 19 percent were sold to fee and recreational fishing establishments.

Information about trout production and consumption is available online from 1995 from the National Agriculture Statistics Service.

Skip Thompson has published a series of reports which build into a resource entitled What Do I Need To Get Started In Trout Farming? There is also some useful information on the care of fingerlings.

George W. Klontz, Professor of Aquaculture, from the Department of Fish and Wildlife Resources, University of Idaho, has published a Manual for Rainbow Trout Production on the Family-Owned Farm. From the introduction:

This presentation is intended for the family-owned and -operated trout farm producing 15-50 tons (30,000-100,000 lbs.) per year. The impetus for my writing this text comes from hearing genuine concerns about rainbow trout in the marketplace. Chefs, restaurateurs, and retailers have stated quite clearly and repeatedly that they expect farmed trout to be of high quality, delivered when needed, and presented in the form required. Stated another way, quality, timeliness, and portion control are the bywords of successful trout production and marketing. Notice that selling price is not among the concerns.

Geoff J. Gooley, from the Australian Rural Industries Research & Development Corporation, has published a report on trout farming in the Australian context. A summary is online, and full document is available for free download.

The trans-Himalayan region encompasses a number of countries situated in the midland and highland areas of the Himalayas, Karakoram and, in a broad sense also, in Hindu Kush and Pamir. The mountains are characterized by a very low level of human development, with full exploitation or overexploitation of the natural resources. Fisheries play an important role in providing food and income to the mountain people. The Symposium on Cold Water Fishes of the Trans-Himalayan Region, held from 10 to 13 July 2001 in Kathmandu, Nepal, was attended by 70 participants from 10 countries. Comprising 32 presentations, the symposium reviewed information, experiences, ideas and findings related to fish and fisheries in the region. Special attention was given to fish species distribution, fishing intensity, socio-economic conditions and livelihoods of fisher communities, as well as to the impacts of environment degradation, conservation measures and aquaculture technologies on indigenous and exotic cold water fish. The symposium highlighted the role of fisheries in providing food and income to people within the trans-Himalayas and Karakoram. Recognizing the need to increase the role of aquatic resources in poverty alleviation, the symposium urged national governments to give greater attention to fisheries development in mountain areas. A number of priority issues were indentified, including collaborative action on a regional scale, which would probably be the most cost-effective way to address these common problems and to share experiences. The recommendations are expected to be addressed in follow-up activities under a trans-Himalayan regional programme.

Contained in the document is a report on research conducted into the domestication of wild golden mahseer (Tor putitora) and hatchery operations leading to the expansion of aquaculture of the species.

The mahseer is a robust species, amongst the largest of the world’s freshwater scaled fish. Six different species have been recognised under the genus, each of which inhabit very different environs. Some are indigenous to tropical waters with a high of 35°C, while others have adapted to sub-Himalayan regions where temperatures dip to 6°C in winter. The golden mahseer, capable of growing to a maximum of 2.75 metres in length and topping 200lb in weight, remains the king of its class.

From the abstract:

Golden mahseer (Tor putitora) are found in most of the south Asian countries including Nepal, India, Bangladesh, Pakistan, Afganistan, Sri Lanka, Myanmar. This popular game fish attains over 50 kg (Thapa, 1994). The population of this fish has been declining because of overfishing, also using destructive fishing methods such as electrofishing and poisoning, and because of the degradation of aquatic environment. India has already identified this fish as endangered (Shrestha, 1988a). Nepal and some other countries are in a stage of enlisting the fish as an endangered species. Strict application of the Aquatic Act and regular restocking of natural water bodies with appropriately sized mahseer can revive their stocks. A joint effort of restocking this migratory fish in the respective water bodies in the region can help to restore their stocks, and all countries should join a programme to revive the fish stocks in the lakes and rivers of their own. Nepal, India and Bangladesh have been attempting to develop large scale seed production technology of mahseer. Information on breeding of golden mahseer is readily available (Tripathi et al., 1977; Pathani and Das, 1979; Masuda and Banstola, 1984; Joshi, 1984; Shrestha 1987, 1988; Shrestha et al., 1990; Sehgal, 1991), but information on domestication of wild broodstock and its hatchery production is scanty (Ogale, this volume). The old practice has been to rear the wild mahseer in captivity. Brood fish grown in captivity can produce the required quantity of seed. Masuda and Banstola (1980) did not foresee the possibility of growing the wild breeders to sexual maturity in captivity. Shrestha (1990) believes that mahseer do not breed in stagnant reservoirs where water circulation is poor. However, the wild breeders grown in earthen ponds, not supplied with running water, attain sexual maturity and exhibit sexual play with the male chasing the female making a loop during the spawning time. The fish spawn twice a year. Its first spawning in April/May is followed by the second one in August/September. Males grown in captivity but it is difficult to sort out females just ready to spawn. This study describes the hatchery operation of wild golden mahseer reared in an earthen pond.

From the preface and introduction:

A National Rice–Fish Farming Systems Symposium was held in China at the Freshwater Fisheries Research Centre of the Chinese Academy of Fisheries Sciences in Wuxi, Jiangsu Province, 4–8 October 1988. China has had a long history of rice–fish farming. As rural areas have been industrialized in recent years, rice–fish farming has gained attention because it is an organic method that combines rice and fish production while maximizing labour and ricefield resources.

Rice has always been the number one grain crop in China in terms of both area and yield. During the 1950s, the tradition of rice–fish farming developed substantially but the benefits were not significant. Fish harvests were poor because the method was based only on traditional experiences and technical difficulties were encountered. However, rice–fish farming developed rapidly and by 1988, 800 000 ha were being harvested with a average yield of 133 kg/ha. In some areas, yields exceeded 3750 kg/ha and many farmers harvested 15 000 kg of rice and 1500 kg of fish per hectare. The incomes of these farmers increased considerably. The techniques of rice–fish farming improved markedly as additional skill and experience were acquired.

Research was focused on the common needs of fish and rice for water, light, and nutrition under local conditions. Many new techniques were developed to suit various locations: ridge and ditch systems; semidry land; ditch manure pits; ditches with floating water; and rice–duckweed–fish systems.

Rice–fish farming is no longer limited to the household economy and to production for personal or family consumption. It is now part of farmland improvement, soil improvement, and environmental protection. Rice–fish farming has increased the productivity of ricefields and is fast becoming an important part of the commodity economy. It has also played a significant role in reforming the structure of rural industries.

Carole R. Engle and Ivano Neira from the Aquaculture/Fisheries Center at the University of Arkansas at Pine Bluff, Arkansas have published a free download (.pdf) document entitled: Tilapia Farm Business Management and Economics:A Training Manual.

The manual offers information initially from the perspective of a farming or investor considering establishing a tilapia-based farm business, using experience and models developed in Kenya. Tilapia has become so widespread and so well documented that almost any dataset can probably be reproduced consistently almost anywhere with only minor regional variance.

From the report:

The tinfoil barb, Barbodes schwanenfeldi, is a common fish found in the international aquarium trade and food markets in Southeast Asia. Tinfoil barbs are a peaceful fish that can reach a length greater than 40 centimeters or 16 inches, and like other, larger barbs, can often live more than 10 years in captivity. In nature, tinfoil barbs are primarily macrophages; that is, they feed on vascular aquatic plants. However, they will eat most commercially prepared diets consisting of vegetable and fish meal proteins.