The Fish Vet's Blog

Recommended Articles

Sent By:	Dr Richmond Loh
I thought you would find this useful on ScienceDirect.

1.	Probiotics and immunity: A fish perspective Review Article Fish & Shellfish Immunology, Volume 29, Issue 1, July 2010, Pages 2-14 S.K. Nayak

a b s t r a c t Probiotics are usually live microorganisms which when administered in adequate amounts confer a health benefits on host. Nowadays, probiotics are also becoming an integral part of the aquaculture practices to obtain high production. The common probiotics that are used for aquaculture practices include Lactobacillus, Lactococcus, Leuconostoc, Enterococcus, Carnobacterium, Shewanella, Bacillus, Aeromonas, Vibrio, Enterobacter, Pseudomonas, Clostridium, and Saccharomyces species. The involvement of probiotics in nutrition, disease resistance and other beneficial activities in fish has proven beyond any doubt. Among the numerous health benefits attributed to probiotics, modulation of immune system is one of the most commonly purported benefits of the probiotics and their potency to stimulate the systemic and local immunity under in vitro and in vivo conditions is noteworthy. Different probiotics either monospecies or multispecies supplementation can eventually elevate phagocytic, lysozyme, complement, respiratory burst activity as well as expression of various cytokines in fish. Similarly, probiotics can stimulate the gut immune system of fish with marked increase in the number of Igþ cells and acidophilic granulocytes. Furthermore, mono-bacterial association studies (with non-probiotic bacterial strains) in gnotobiotic fish also indicate the up-regulation of various immune related genes. Though the exact mode of action of probiotics is yet to be established in any animal including fish, probiotics often exert host specific and strain specific differences in their activities. Various factors like source, type, dose and duration of supplementation of probiotics can significantly affect the immunomodulatory activity of probiotics. The review is therefore, aiming to highlight the immunomodulatory activity of probiotics and also to evaluate the factors that regulate for the optimum induction of immune responses in fish.

This email has been sent to you by ScienceDirect, a division of Elsevier B.V., Radarweg 29, 1043 NX Amsterdam, The Netherlands, Tel.+31 20 485 3911. ScienceDirect respects your privacy and does not disclose, rent or sell your personal information to any non-affiliated third parties without your consent, except as may be stated in the ScienceDirect online privacy policy. By using email or alert services, you agree to comply with the ScienceDirect Terms and Conditions. © 2011 ScienceDirect. All rights reserved. Any unauthorized use, reproduction, or transfer of this message or its contents, in any medium, is strictly prohibited. ScienceDirect® is a registered trademark of Elsevier B.V.

Just how do salmon find their way back to their spawning grounds? How do lampreys find their way to suitable spawning sites? They have the ability to “smell” their way. Salmon remember the exact chemical composition of the water in which they were hatched. Lampreys are able to detect minute amounts of hormones of resident “larval” lampreys. These are important for their survival as a species.

As such, fishes are inadvertently, great indicators of ecosystem health. So much so that they can sense chemicals that are beyond the detectable limits of even the most modern laboratory equipment.

There have been reports of higher than normal prevalence of female fishes in some waterways, influenced perhaps by chemical and/or hormones. This article details the factors that affect gender determination in fishes.

Begin forwarded message:

From: Dr Richmond Loh<thefishvet>
Date: 29 November 2011 12:36:14 AWST
To: thefishvet
Subject: Recommended article on ScienceDirect

Recommended Articles

Sent By:	Dr Richmond Loh
I thought you would find this useful on ScienceDirect.

1.	Sex determination and sex differentiation in fish: an overview of genetic, physiological, and environmental influences Review Article Aquaculture, Volume 208, Issues 3-4, 21 June 2002, Pages 191-364 Robert H. Devlin, Yoshitaka Nagahama

A great deal of information is known regarding the process of sex differentiation in fish, and the mechanisms involved in primary sex determination are now beginning to be defined. A range of gonadal differentiation types have been described for fish, including gonochoristic species possessing purely ovarian or testicular tissues, as well as hermaphroditic species that can initially mature either as males (protandrous) or females (protogynous). Sex determination in fish is a very flexible process with respect to evolutionary patterns observed among genera and families, and within individuals is subject to modification by external factors. These influences can affect the fate of both somatic and germ cells within the primordial gonad, and include the action of genetic, environmental (e.g. temperature), behavioural, and physiological factors. Exogenous sex steroids administered at the time of sex determination can strongly influence the course of sex differentiation in fish, suggesting that they play a critical role in assignment of gonad determination as well as subsequent differentiation. Detailed information is available from fish systems describing the production of sex steroids, as well as the enzymes involved in steroid production. Both estradiol and the maturation hormone 17α, 20β-dihydroxy-4-pregnen-3-one (17α, 20β-DP) are produced by a two-step process involving different cell layers in the gonad, and have effects on the differentiation of gonadal and nongonadal tissues. Gonadal development and differentiation in some fish is also controlled by hormones from the pituitary gland (gonadotropins) that are regulated by release hormones (GnRH) and other neuroendocrine and gonadal factors. Genetic determination of sex in fish can involve monogenic or polygenic systems, with factors located on the autosomes or on sex chromosomes. In the latter case, both male (XY) and female (ZW) heterogametic systems have been described, as well as many subtle variations on these themes. Sex chromosomes are found in approximately 10% of fish species examined, and sex-linked phenotypic traits, and protein and molecular genetic markers have been identified in several fish systems. Some species of fish reproduce gynogenetically, producing all-female populations. Several gene families known to be involved in sex determination in other vertebrates have recently been shown to be similarly involved in fish, suggesting conservation of sex determination pathways. The lability of sex-determination systems in fish makes some species sensitive to environmental pollutants capable of mimicking or disrupting sex hormone actions. Such observations provide important insight into potential impacts from endocrine disruptors, and can provide useful monitoring tools for impacts on aquatic environments.

This email has been sent to you by ScienceDirect, a division of Elsevier B.V., Radarweg 29, 1043 NX Amsterdam, The Netherlands, Tel.+31 20 485 3911. ScienceDirect respects your privacy and does not disclose, rent or sell your personal information to any non-affiliated third parties without your consent, except as may be stated in the ScienceDirect online privacy policy. By using email or alert services, you agree to comply with the ScienceDirect Terms and Conditions. © 2011 ScienceDirect. All rights reserved. Any unauthorized use, reproduction, or transfer of this message or its contents, in any medium, is strictly prohibited. ScienceDirect® is a registered trademark of Elsevier B.V.

Believe it or not, Herbal medicines work in fish!

I have attended a house call where one of the fish owners was a Chinese herbal doctor. With the aid of some ginseng, she managed to bring back fish that was beyond the cure of western medicine.
The paper below provides scientific evidence/explanations on how these substances produce their effects.

From: Dr Richmond Loh<thefishvet>
Date: 29 November 2011 12:36:56 AWST
To: thefishvet
Subject: Recommended article on ScienceDirect

Recommended Articles

Sent By:	Dr Richmond Loh
I thought you would find this useful on ScienceDirect.

1.	Impact of plant products on innate and adaptive immune system of cultured finfish and shellfish Review Article Aquaculture, Volume 317, Issues 1-4, 4 July 2011, Pages 1-15 Ramasamy Harikrishnan, Chellam Balasundaram, Moon-Soo Heo

Aquaculture is one of the fastest growing food-producing sectors around the world. Among various kinds of cultivated organisms many marine and freshwater finfish and shellfish species constitute an important industry with their production increasing every year. Recently due to intensive farming practices infectious diseases pose a major problem in aquaculture industry, causing heavy loss to farmers. A number of approaches have been made to control diseases including sanitary prophylaxis, disinfection, and chemotherapy with particular emphasis on the use of antibiotics. However, the application of antibiotics and chemicals in culture is often expensive and undesirable since it leads to antibiotic and chemical resistance and consumer reluctance. Therefore immunostimulants such as glucan, chitin, lactoferrin, levamisole, and some medicinal plant extracts or products have been used to control fish and shellfish diseases. In this regard the medicinal plant extracts and their products act as immunostimulants modulating the immune response to prevent and control fish and shellfish diseases. The immunostimulants mainly facilitate the function of phagocytic cells, increase their bactericidal activities, and stimulate the natural killer cells, complement, lysozyme activity, and antibody responses in fish and shellfish which confer enhanced protection from infectious diseases. Currently increased consumer demand for perfection in fish and shellfish farms has put new dimensions to the quality, safety, elimination of concomitant pollutants, antibiotics, and carcinogens during the production process. In this context plants or their byproducts are preferred since they contain several phenolic, polyphenolic, alkaloid, quinone, terpenoid, lectine, and polypeptide compounds many of which have been shown to be very effective alternatives to antibiotics, chemicals, vaccines, and other synthetic compounds. In aquaculture the herbal medicines are also known to exhibit anti-microbial activity, facilitate growth, and maturation of cultured species; besides under intensive farming the anti-stress characteristics of herbs will be of immense use without posing any environmental hazard. Administration of herbal extracts or their products at various concentrations through oral (diet) or injection route enhance the innate and adaptive immune response of different freshwater and marine fish and shellfish against bacterial, viral, and parasitic diseases. Even an overdose of immunostimulants may induce immunosuppression without side effects but helps to reduce the losses caused by disease in aquaculture. The present review describes the role of medicinal herbs and their products on innate and adaptive immune response of finfish and shellfish.

This email has been sent to you by ScienceDirect, a division of Elsevier B.V., Radarweg 29, 1043 NX Amsterdam, The Netherlands, Tel.+31 20 485 3911. ScienceDirect respects your privacy and does not disclose, rent or sell your personal information to any non-affiliated third parties without your consent, except as may be stated in the ScienceDirect online privacy policy. By using email or alert services, you agree to comply with the ScienceDirect Terms and Conditions. © 2011 ScienceDirect. All rights reserved. Any unauthorized use, reproduction, or transfer of this message or its contents, in any medium, is strictly prohibited. ScienceDirect® is a registered trademark of Elsevier B.V.

One of my friends swears that his koi carp loves peanuts. I often wondered about this. This new study shows that peanuts may be suitable for certain fish (but it does not replace a varied and balanced diet).

Journal of Applied Aquaculture
Volume 23, Number 4 (October 2011)
	The Potential of Groundnut (Arachis hypogaeaL.) By-Products as Alternative Protein Sources in the Diet of Nile Tilapia (Oreochromis niloticus)
	Authors:	N.W. Agbo 1
	Author Affiliations:	1: Institute of Aquaculture, University of Stirling
	Source:	Journal of Applied Aquaculture, Volume 23, Number 4 (October 2011)
	Page Numbers:	367 – 378
	Available Full Text:	Full Text: Subscription Required to view full text Format: PDF Size: unknown Location: Publisher’s Site Authentication: EBSCOhost EJS
	Abstract:	The nutritional suitability and cost effectiveness of groundnut cake (GNC) and groundnut husk (GNH) as protein sources in the diet of Nile tilapia (Oreochromis niloticus), mean initial weight 4.24 ± 0.20 g, was evaluated over a 56-day growth period. Five isonitrogenous (320 gkg-1), isolipidic (100 gkg-1), and isoenergetic (18 KJg-1) test diets were formulated in which GNC proteins replaced fish meal (FM) protein at levels of 25% and 50%, and GNH protein at 10% and 20%. The control diet had FM as the sole protein source. The growth experiment was conducted in plastic tanks in a recirculation system; each dietary treatment was in triplicate. After feeding fish at 4%–6% body weight per day, GNC and GNH protein replacements up to 50% and 20%, respectively, did not significantly (P < 0.05) affect growth and feed utilization. The study indicated that GNC and GNH protein could replace at least 50% and 20% of fish meal protein, respectively, in the diet of O. niloticusfingerlings without adversely affecting growth, feed efficiency, whole body composition, and nutrient digestibility. Generally the GN by-products-based diets were more cost-effective than the fish meal-based diet, particularly GNH replacing 20% fish meal protein.
	Citation:	N.W. Agbo . The Potential of Groundnut (Arachis hypogaeaL.) By-Products as Alternative Protein Sources in the Diet of Nile Tilapia (Oreochromis niloticus). Journal of Applied Aquaculture, Volume 23, Number 4 (October 2011), pp. 367-378,
	URL:	http://ejournals.ebsco.com/direct.asp?ArticleID=4FDEB60156B609A0CEE6

Free copies of Fish Vetting Essentials will be given away to celebrate the 1 month anniversary of its release!

The first 3 buyers of the portable microscope during the month of December will receive two complimentary copies of the Fish Vetting Essentials book.

That’s a value of $200! One for a friend and one for keeps!

Check out the online store –
http://thefishvet.com.au/shop/shopping.html

Scandanavian fisheries ministers sign agreement prohibiting fish discards
http://www.fishupdate.com/news/fullstory.php/aid/16637

FISHERIES ministers from Norway, Sweden and Denmark have signed a joint declaration to prohibit discarding of fish in the Skagerrak from 2013.

Discarding of fish is a huge problem in fisheries worldwide and is caused by fish being caught that are over quota, unmarketable or cannot be landed.

Louize Hill, head of Marine &amp; Fisheries Policy at WWF European Policy Office, said: “Discarding of fish is a terrible waste of marine resources. Together with overfishing, this represents a massive threat for the world’s fish stocks. Banning discards can be an effective way to end this waste, when accompanied with measures to stop the fish that would be discarded being caught in the first place.”

Norway already has a discard ban accompanied by regulations that aim to reduce bycatch. At present in the EU, however, fishermen are required to discard fish that cannot be legally landed because they are below a certain minimum size, or are over quota, and there are few incentives for fishermen to adopt selective fishing practices that would mean these fish would not be caught in the first place.

“The Common Fisheries Policy has not halted overfishing in the past decades, and so is under reform to try and address this. Tackling discards is high on the agenda of the Commission,” continues Louize Hill. “But, a ban alone is not enough, we need accountability for catches as well as selective fishing gear and practices to be in place at the same time.”

—
Yours sincerely,

Dr Richmond Loh
BSc BVMS MPhil MANZCVS (Aq & Pathol)
The Fish Vet, Perth, Western Australia.
Veterinary Medicine for fish.
http://www.thefishvet.com.au
Ph: +61 (0)421 822 383

From today’s West

All you ever wanted to know about abalone is here in this short document. It contains information on their anatomy (form & function), their biological and environmental requirements as it pertains to abalone farming and also routine diagnostic techniques used to investigate abalone health and diseases.

Summary – Abalone anatomy, biology, requirements and lab testing protocols

From today’s West.

> ACTION ON SHARK FINNING WELCOME
> http://www.fishupdate.com/news/fullstory.php/aid/16623
>
>
>
> Commission follows Scotland’s lead to strengthen ban on “barbaric” shark finning. >
> The European Commission has adopted a proposal for a complete ban on the practice of shark finning – where fins are sliced off sharks when vessels are at sea, and the dead or dying shark is thrown back to sea. This will now require to also be signed off by the European Parliament before it comes into force. >
> The move follows the Scottish Government’s lead, which strengthened the shark finning ban for Scottish vessels in January 2010, the first country to do so. >
> Scottish Fisheries Secretary Richard Lochhead said: “Sharks are part of Scotland’s rich marine biodiversity and I am delighted that the Commission has finally seen sense and followed our lead by closing loopholes in the shark finning ban. Until now it has been possible for other EU vessels to remove fins from sharks when in our waters, therefore I’m relieved that this is to be addressed and call on all MEPs to support the strengthened ban. >
> “Some shark populations are very vulnerable and shark finning is no more acceptable than the elephant ivory hunters of the last century. There is no place for such destructive and wasteful practices in a modern, sustainability-focused fishing industry. >
> “I urge the Commission to continue to look at Scotland’s example for progressive measures to protect sharks. In June we announced new rules, which will come into force next year, to further increase protection for vulnerable species, including preventing fishermen landing some shark species and only permitting catch and release by anglers.” >
> In June the Scottish Government announced new m asures to protect vulnerable species of shark, skate and ray. Find out more at: http://www.scotland.gov.uk/News/Releases/2011/06/23155002 >
> Details on the European Commission announcement can be found at: http://ec.europa.eu/fisheries/index_en.htm >
>