The Fish Vet's Blog

Dr Richmond Loh has achieved Expert Author status for EzineArticles.com. Ezinearticles.com is an electronic website that provides an educational forum for consumers researching a particular topic. Dr Loh has enjoyed teaching undergraduate and post-graduate veterinary students alike which is why he began publishing for ezinearticles.com. Contact Dr Loh for veterinary advice on a variety of topics pertaining to fish health.

Dr Loh is a registered veterinarian and has expertise in aquatic animal health. Additionally, Dr Loh’s new book, “Fish Vetting Essentials” is paving the way to help veterinarians enter this under-serviced field of veterinary science.

Check out Dr Loh’s article on fish mycobacteriosis.

One of the purported major health issues that is faced by the tuna industry in South Australia is blood flukes. These are flatworms that live within the blood vessels and the heart of the fish, sometimes lodging in different organs where they evoke severe inflammation and cause death to the fish.

To remedy the situation, fish are fed a diet containing the anthelmintic praziquantel with good results. The abstract below is some of the work that was generated…. But is there a better option than having to medicate the fish?

If fish were slaughtered pen-side and all the discards flow back into the same waters where the fish are reared, then diseases such as these would become amplified. Fortunately, all byproducts are captured by gutters and bins around harvest tables and are transported to an onshore processing facility for rendering.

Good management options should always be sought before reaching for medication.

Aquaculture
Volume 337, Number 1 (March 2012)
	In vitroand in vivoefficacy of anthelmintic compounds against blood fluke (Cardicola forsteri)
	Authors:	Paul Hardy-Smith, David Ellis, John Humphrey, Mathew Evans, Daryl Evans, Kirsten Rough, Victoria Valdenegro, Barbara Nowak
	Author Affiliations:	no affiliations available
	Source:	Aquaculture, Volume 337, Number 1 (March 2012)
	Page Numbers:	39 – 44
	Available Full Text:	Full Text: Subscription Required to view full text Format: PDF Size: Unknown Location: Publisher’s Site Authentication: Publisher’s Site
	Abstract:	Blood fluke, Cardicola forsteri, infects Southern Bluefin Tuna, particularly during ranching. Efficacy of four anthelmintics was tested against this parasite. There was an agreement between in vitroand in vivoresults. Praziquantel was the only effective anthelmintic. It was the most potent anthelmintic in decreasing fluke responsiveness in vitro, with concentrations ranging between 1.5µg/mL and 200µg/mL stopping adult fluke response within less than 5min. In vivo, both the higher (150 mg/kg) and the lower (75 mg/kg) dose praziquantel treatment resulted in a significant reduction of the number of flukes present in the hearts. A significant effect of treatment on the mean number of blood fluke eggs per cm2of tuna myocardium was observed, with fish treated with either of the two doses of praziquantel having at least 6 times lower numbers of eggs in their hearts. Control fish and fish treated with praziquantel (both doses) and lower dose Closal had very low average number of eggs per cm2of gill and were significantly lower than in fish treated with fenbendazole. While this research shows that praziquantel is the treatment of choice against blood fluke, C. forsteri, further research is needed to determine optimum dose, best treatment application method, palatability and any potential side effects.
	Citation:	Paul Hardy-Smith, David Ellis, John Humphrey, Mathew Evans, Daryl Evans, Kirsten Rough, Victoria Valdenegro, Barbara Nowak . In vitroand in vivoefficacy of anthelmintic compounds against blood fluke (Cardicola forsteri). Aquaculture, Volume 337, Number 1 (March 2012), pp. 39-44,
	URL:	http://ejournals.ebsco.com/direct.asp?ArticleID=41F6BCDCE248CFBEB2C6

The abstract below shows that fish protein may be substituted to some degree with plant proteins…..

But what effect will it have on their long-term nutritional needs?

Fish are generally marketed to consumers because they are a healthy choice and high in omega-3 fatty acids. Fish derive much of this from what they eat. So what effect will it have on the fatty acid content of the fish when it comes time to slaughter?

Perhaps we should turn to bread for our daily source of iodine, omega-3, fibre…..

Create Alert Add to Favorites Mark
Aquaculture
Volume 337, Number 1 (March 2012)
	Replacing fishmeal with blends of alternative proteins on growth performance of rainbow trout (Oncorhynchus mykiss), and early or late stage juvenile Atlantic salmon (Salmo salar)
	Authors:	Gary S. Burr, William R. Wolters, Frederic T. Barrows, Ronald W. Hardy
	Author Affiliations:	no affiliations available
	Source:	Aquaculture, Volume 337, Number 1 (March 2012)
	Page Numbers:	110 – 116
	Available Full Text:	Full Text: Subscription Required to view full text Format: PDF Size: Unknown Location: Publisher’s Site Authentication: Publisher’s Site
	Abstract:	The purpose of this study was to evaluate blends of alternate proteins as replacements for fishmeal in diets for rainbow trout (Oncorhynchus mykiss) and to use the results to develop and test alternate protein blends in diets for juvenile Atlantic salmon (Salmo salar). Nine experimental diets in which protein blends replaced 63%, 82% or 100% of fishmeal in the formulation (20, 10, and 0% fishmeal) were fed to rainbow trout (initial weight 19.5g) for 12weeks. Weight gains of trout fed diets containing the soy protein concentrate-based blend and the fishmeal control diet were similar, except at the 100% fishmeal replacement level, and significantly higher than that of trout fed diets containing the other blends. The soy protein blend and another based on wheat gluten meal were modified slightly and evaluated in early stage Atlantic salmon juveniles (initial weight 5.5g). Protein blends replaced 50%, 66% or 84% of fishmeal (30, 20 or 10% fishmeal). Weight gains of early stage juvenile salmon after 18weeks of feeding were significantly lower and feed conversion ratios higher when fed diets containing either blend compared to the fishmeal control diet, and gains decreased as level of fishmeal replacement increased. Blends were then modified further and tested in advance stage salmon juveniles (initial weight 31.5g). These blends were solely either all-plant protein-based or contained poultry by-product meal. Both blends were evaluated with or without addition of Spirulinaalgae meal. Alternate protein blends completely replaced fishmeal in experimental diets. After 12weeks of feeding, no differences in weight gain or feed conversion ratios were measured among groups fed experimental diets containing protein blends or the fishmeal control diet. Replacement of fishmeal with alternative protein blends in diets for early stage juvenile salmon is not recommended and the penalty in growth is severe. Fishmeal can be completely replaced in diets for late stage salmon over 30g without compromising fish performance or using land animal protein ingredients in feed formulations.
	Citation:	Gary S. Burr, William R. Wolters, Frederic T. Barrows, Ronald W. Hardy . Replacing fishmeal with blends of alternative proteins on growth performance of rainbow trout (Oncorhynchus mykiss), and early or late stage juvenile Atlantic salmon (Salmo salar). Aquaculture, Volume 337, Number 1 (March 2012), pp. 110-116,
	URL:	http://ejournals.ebsco.com/direct.asp?ArticleID=47808B9B64BB8CDDEC28

Four sharks have been sighted off the coast of Yanchep and the beaches in the vicinity remains closed (http://www.watoday.com.au/wa-news/whale-carcass-attracts-sharks-to-metro-beaches-20120219-1tgvn.html).

This news article prompted me to think about the age old debate about whether sharks would eat humans. The prevailing socially acceptable answer out there is that they don’t. But are we underestimating their intelligence?

As a fish keeper and a veterinarian, I’ve read about, kept and observed numerous different fish species. One thing about their feeding habits is that they can learn to eat different foods. They can learn off their own species, and they can learn off other species. They can accept all types of live feeds, chopped up fresh meats and all sorts of dried foods. They will have a go and nibble and things to see if it’s edible. They will sample and eat things that they would never see in nature (e.g. cuttlefish and octopus to freshwater tropical ornamental fishes and boiled egg yolk to baby fish). So, why would a shark differ in their culinary behaviour?

So when a shark is given the opportunity to eat a human dressed like a seal, what do you think the shark’s next move would be?

NEWS, REVIEWS AND OPINIONS ON THE LATEST FISHKEEPING GADGETS.

Check out what’s new – some pages from Practical Fish Keeping Magazine which can be downloaded from the link below, courtesy of Nathan Hill.

Practical Fish Keeping – New Gadgets

Fish are unique in their ability to absorb minerals not only from their diets but also from water!