I have a habit of researching things that lead me down Rabbit holes. In one such search I came across a PhD Thesis paper from 2018 entitled..
Trujillo-González, Alejandro (2018) Parasite threats from the ornamental fish
trade. PhD Thesis, James Cook University.
https://researchonline.jcu.edu.au/64...018_thesis.pdf
The Paper focuses on Australia's Bio-Security and its shortfalls with regards to Ornamental fish.
Quote:
Biosecurity can be defined as an approach designed to prevent or decrease the
transmission of naturally occurring infectious diseases and pests in crops and livestock
(Koblentz 2010). This definition has been expanded to include invasive exotic species and
their associated threats to the economy and the environment (Meyerson and Reaser 2002).
Depending on the context, the definition of biosecurity has been modified to suit the aims and
requirements of independent organisations. For example, the Food and Agriculture
Organization of the United Nations (FAO) defines biosecurity as “a strategic and integrated
approach that encompasses the policy and regulatory frameworks (including instruments and
10
activities) for analysing and managing relevant risks to human, animal and plant life and
health, and associated risks to the environment” (FAO 2007). For the purpose of this thesis,
biosecurity is defined as:
‘A set of measures or procedures designed to protect countries against the risks that may
arise from exotic pests entering, establishing and spreading in local ecosystems, thereby
threatening the economy and endemic environment
For me it was eye opening because Australia has the worlds most strict Bio-security in place. Its been a source of frustration to many hobbyists there In that its very difficult to bring things into Australia. The policies there are to protect the unique Ecology of Australia and its economies from invasive organisms, parasites, and diseases. Personally I feel the USA could and should learn from it. I have seen too many cases of invasive organisms destroying native species here. Obviously even Australia's policies are not perfect and come with significant downsides . Trujillo-González's thesis focuses on some of these.
Its a very interesting read with a fair amount of History and data in it. What I keyed into was a section where He discusses Parasites (chapter 3) . Apparently the importation of tropical fish has to be accompanied by health certificates from the exporting country stating the fish are healthy and parasite free. That is standard for alot countries but honestly is nothing more than a rubber stamp (My Opinion)
Attachment 139603
Attachment 139604
So as for the Parasites discussion...
Flukes...Quote:
37
CHAPTER 3
SURVEY OF PARASITES IN THE AUSTRALIAN ORNAMENTAL FISH
TRADE
Abstract
The ornamental fish trade provides a pathway for the global translocation of aquatic parasites.
I examined a total of 1,020 fish imported from southeast Asia, including freshwater and
marine fish species, for myxozoan and monogenean parasites. Fish were received following
veterinary certification that they showed no clinical signs of pests and diseases from the
exporting country and visual inspection at Australian border control. Myxozoan parasites
infected 8 of 13 freshwater populations and 8 of 12 marine populations. 18 putative types of
myxozoan parasites and 14 putative types of monogenean were identified using a combined
morphological and molecular approach. A total of 12 morphologically distinct Myxobolus
spores were detected amongst all Carassius auratus Linnaeus, 1758 populations. Myxidium
spores were detected in Helostoma temminckii Cuvier, 1829, and four putative Ceratomyxa
sp. spores were detected in Cheilodipterus quinquelineatus Cuvier, 1828, Pterapogon
kauderni Koumans, 1933, and Zoramia leptocantha (Bleeker, 1856). Monogenean diversity
included seven Dactylogyrus spp. (including Dactylogyrus vastator Nybelin, 1924), and three
Gyrodactylus spp. infecting goldfish, C. auratus. Dactylogyrus ostraviensis Řehulka, 1988,
infected rosy barb, Pethia conchonius Hamilton, 1822, while two Trianchoratus spp. infected
three spot gourami, Trichopodus trichopterus Pallas, 1970 and pearl gourami Trichopodus
leerii Bleeker, 1852. Urocleidoides reticulatus Mizelle et Price, 1964, infected guppy,
Poecilia reticulata Peters, 1859. Australian import conditions require mandatory treatment
for goldfish with parasiticide (e.g. trichlorfon, formaldehyde, sodium chloride) for the
presence of gill flukes (D. vastator and Dactylogyrus extensus Mueller et Van Cleave, 1932)
prior to export. The discovery of myxozoan and monogenean infections, including D.
vastator in goldfish, show that pre-export health requirements and visual inspection did not
reliably prevent parasite infections. Inspection prior to exportation and at border control must
account for the highly cryptic nature of parasites and consider alternatives to current pre-
export conditions and visual inspection at border con
Quote:
Despite pre-import and border conditions perceived to be stringent, the cryptic nature of
the parasitic monogeneans found in this study suggests they would likely remain undetected
in quarantine. All fish populations sampled for this study were within quarantine conditions
as required by Quarantine Services, meaning that had the fish been destined for sale, all
populations would still require a final quarantine period of a minimum of seven days (21 days
for goldfish) in an approved facility provided by the importer (DAWR 2018). However,
following this period, only visual inspection is required to release fish from quarantine
(DAWR 2018) which would likely permit the distribution of fish infected with monogeneans
into the broader retail industry, unless the infections had manifested, and fish exhibited
clinical signs of disease. Therefore, it is imperative to review the efficacy of visual
inspections at border control to detect parasite infections and consider alternative detections
tools as effective preventive measures for Australian biosecurity
This didn't really surprise me but what the authors proposed and documented method of dealing with identifying parasites is extremely interesting. .. DNA / with PCR amplification to detect pathogens and parasites in imported Fish!
Quote:
CHAPTER 5
PARASITE DETECTION IN THE ORNAMENTAL FISH TRADE USING
ENVIRONMENTAL DNA
Abstract
Effective border control relies on stringent biosecurity protocols to detect and prevent
introductions of exotic pests and diseases. Detection of pathogens and parasites in the live
ornamental fish trade using environmental DNA (eDNA) techniques has the potential to
improve current biosecurity practices. We examined water samples from 11 target
consignments (cyprinids susceptible to Dactylogyrus spp. infections) and seven non-target
fish consignments (non-cyprinids, not susceptible to Dactylogyrus spp. infections) imported
from Southeast Asia to Australia for the presence of eDNA from five Dactylogyrus species
(Monogenea: Dactylogyridae). A four-step predictive framework was used to predict putative
positive and putative negative detections from quantitative PCR assays. Both target and non-
target consignments were positive for Dactylogyrus spp. eDNA as confirmed by Sanger
sequencing. Positive detections for Dactylogyrus spp. eDNA in non-target fish consignments
demonstrates the possibility of source water contamination, limiting the applicability of
eDNA screening methods at border control. This study suggests eDNA screening should be
tested during pre-export quarantine periods to avoid false positive detections at border
control, highlights the utility of a predictive framework to avoid both false positive and
negative detections, and discusses the potential for eDNA to advance ornamental fish trade
biosecurity
Quote:
In conclusion, this first attempt at applying eDNA to ornamental fish parasite
biosecurity highlights both the utility of incorporating molecular methods into biosecurity
protocols as well as the limitations that need to be addressed if future applications and full
integration are to be successful. We present a novel and comprehensive four-step predictive
framework (Figure 22) for the accurate interpretation of species-specific eDNA data and
reduce false positive and false negative detections generated by Sybr-based qPCR assays.
The interpretability and reliability of eDNA detection at border control specifically is limited;
however, eDNA screening could prove highly valuable if implemented following pre-export
quarantine periods. Further research needs to address limitations encountered in this study
and test the viability of eDNA-based detection methods in other stages of quarantine and
biosecurity surveillanc
Quote:
This research examined the potential use of eDNA in biosecurity and border control.
Although this study detected species-specific eDNA from five Dactylogyrus species infecting
ornamental goldfish and rosy barb populations imported to Australia, results indicated the
high possibility of false positive detections associated with contaminated source water
(Chapter 5). The use communal source water by exporting companies to rear and export
ornamental fishes would impede the use of eDNA at border control as a reliable detection
tool. Furthermore, this research showed that eDNA screening was unreliable when used to
detect low parasite intensities of Neobenedenia girellae in a simulated ‘export scenario’.
Lastly, the timeframe needed to collect, extract, and test water samples for parasite eDNA in
this study was considerably time consuming. Therefore, this research shows that eDNA
screening methods are not viable for aquatic parasites at border control, given the high
possibility of false positive detections, lack of diagnostic sensitivity in detecting subclinical
parasite intensities, and the considerable amount of time needed to test water samples for
target eDNA, which is unfeasible within the limited timeframe of border control inspection.
These results should not negate the consideration of eDNA approaches to other scenarios for
detection of pathogens at border control (e.g. the detection of viral pathogens in animal feeds,
Whittington and Chong 2007)
There is a lot of really good info in this Thesis . Imagine that you no longer have to deal with Gill Flukes in imported fish. If theres a way to quickly screen for them using bag water its a huge deterent for exporters to send parasite infected fish.,, and there would be a way to check for gill flukes without gill scrapes.This has really significant applications!
Probably a bit much for a sunday morning read but please do when you can.
Also of interest .. they used DNA to detect Myxozoans. These are the group of organisms that the pathogen that causes "whirling disease (Myxobolus cerabralis)" belongs to. Generally everyone focuses on the cold water associated Myxobolus cerabralis but there are many warm water species too.. read here..https://edis.ifas.ufl.edu/publication/FA201
Just sharing what I though was just a really great paper.
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