Preventing monogenean

gill parasites

in marine fish

APEX BRANCHIA C

Introduction

• Parasitism : symbiotic relationship where one organism, the

parasite, benefits at the expense of the other, the host

• Often complex life cycles

• Abundant in nature

• Most are microscopic and difficult to diagnose

• Aquaculture : increasing economic impacts from parasitic

infestations

• Intensification of production system

• Secondary bacterial infections or parasites causing mortality

• Affecting final product quality (eg sealice, gill color)

Important parasites in Aquaculture

PROTOZOA: single cell• Ciliates, eg I. multifiliis white spot

• Flagellates

• Microsporidae: intracellular parasites

• Coccidae: intracellular parasites

• Myxosporidae: endo parasites

PLATYHELMINTHES: flatworms• Monogenean trematodes (Flukes), eg Gyrodactylus

• Nematodes (Roundworms)

• Cestodes (Tapeworms)

PARASITIC CRUSTACEANS AND LEECHES: • Larger parasites, eg sea lice

Monogenean parasites (“gill flukes”) in marine fish

Important ectoparasites in marine and freshwater fish

Main species in Mediterranean marine fish:

Seabass:

• Diplectanum aequans

• Diplectanum laubieri

• Serranocotyle labracis

Seabream:

• Sparicotyle (syn. Microcotyle) chrysophrii

• Dactylogyrus (syn. Furnestinia) echeneis

Clinical signs:

• gill irritation and increased mucus production

• Loss of red coloration of gills

• Asphyxia (high level of infestation)

Light microscopic image of

Sparicotyle chrysophrii

Diplectanum aequans

Importance of prevention

Treatment

• Limitations of drugs and chemicals: • Difficult application (eg cage farming)

• Regulatory issues & consumer concerns

� Prevention strategies:• Bio-security & hygiene measures

• Balanced feed formulas & good farming practice

• Specific health promoting additives with natural anti-parasiticaction

• Direct action on gut parasites in the digestive tract

• Indirect action on ecto parasites: – Natural anti-parasitic compounds absorbed and circulating in

the blood stream

– Enhanced immune-response (eg. mucus quality & thickness)

Research on prevention of fish parasites through functional feed additives

COMPLEX !

• Many different species of fish and parasites

• Complex interactions (among different parasites, with

secondary bacterial infections, seasonal ambient

conditions, ...)

• Life cycles not fully understood

• Challenge protocols under lab conditions still under

development

• Lab results (in vitro or in vivo challenge) often not

reproducable under production conditions

Novel field of academic research

Prevention of monogenean gill parasites using natural additives: caprylic acid

Rigos et al. (2013)

1. Verification of absorption and circulation of the anti-parasitic

component administered through the feed:• Single in-feed administration of 100 or 200 mg/kg caprylic acid to Gilthead seabream

• Caprylic acid absorbed and circulating in the blood serum, present in skin and gills

Skin caprylic acid concentration

Gill caprylic acid concentration

Serum caprylic acid concentration

Prevention of monogenean gill parasites using natural additives: caprylic acid

FARM 1: prevention effective !low initial prevalence (44-47%)

and mean intensity (1.1-1.5 adults)

FARM 2: treatment not effectivehigh initial prevalence (100%)

and mean intensity (up to 17 adults)

Rigos et al. (2013)

2. Evaluating efficacy under farm conditions- Caprylic acid (200 mg/kg of feed) to Gilthead seabream cages during 60 d

- Monitor infection intensity Sparicotyle chrysophrii

Importance of synergistic action of botanical extracts

• Effects of single and combined use of two

herbal extracts to prevent Dactylogyrus on

goldfish (Carassius auratus)

• RDZ (Dioscorea zingiberensis)

• SGB (Ginkgo biloba)

• Measure anti-parasitic efficacy by exposing

infested fish to a range of concentrations

of herbal extracts

• Anti-parasitic Efficacy (48h EC50)

• Single components (SGB or RDZ):

3.5 mg/L

• Combination (SGB/RDZ 5:5):

1.5 mg/L

Jiang et al. 2014

3 fold decrease of effective dosage

thanks to synergistic action

Research on prevention of fish parasites through functional feed additives

• Complex

• New field of academic research

• Most studies focussed on single component additives

Nutriad’s approach:

• empiric work in the field with selected customers

or research institutes

• synergistic additive cocktails targeting multiple

mode of actions

Department of Fish Pathology, Faculty of Fishery,Nong Lam University of Hochiminh City, Vietnam

APEX AQUA enhances resistance to monogenean gill

parasites in Pangasius catfish (Pangasianodon

hypophthalmus)

(Coutteau, Nguyen Huu Thinh, Eskinazi and Huyen Dieu Nguyen

– Aquaculture Asia-Pacific, Sept-Oct 2010)

Nutriad’s innovative research on prevention of monogenean gill parasites

Monogenean gill parasites in Pangasius

Experimental Design & Pond Setup

• Triplicate cages (4x2 m) per

treatment

• Stocking Density: 80 fish/m2

(640/cage); fingerlings of 9-

11g live weight

• Experimental diets (extruded

commercial basal feed) fed

for 8 weeks

• Treatments

� Control: No Apex

� NT0.05: Apex 0.5kg/MT

� NT0.1 : Apex 1.0kg/MT

NT0.05 (3) Control (1) Control (3)

Control (2)

NT0.1 (2)

NT0.1 (3) NT0.05 (2)

NT0.05 (1) NT0.1 (1)

Results - Performance

Control Apex 0.5 Apex 1.0

Start Weight (g) 9.95a 9.90a 10.26a

Final Weight (g) 67.55a 69.92ab 71.36b

Weight Gain (g) 57.60a 60.02a 61.1a

Specific Growth Rate (%/day) 3.01a 3.05a3.13b

(+4%)

Feed Intake (g/fish/day) 1.46a 1.49a 1.44a

Feed Conversion Ratio 1.42a 1.41a1.34b

(-5.6%)

Survival Rate (%) 83.31a 84.92a 90.01a

abc – P<0.05

Intensities of monogenean infection in Pangasius fed different levels of a blend of botanical extracts during 8 weeks.

INTENSITY OF INFECTION

(average number of monogenea per fish)

0

1

2

3

4

5

6

7

8

9

10

0 1 2 3 4 5 6 7 8

WEEKS

MO

NO

GE

NE

A P

ER

FIS

H CONTROL

APEX 0.5 kg/MT

APEX 1 kg/MT

HEAVY

RAIN

a

a

a

a

a aa

a

b

a

b a

b

b

b

b

b

c bc

c

Prevalence of monogenean infection in Pangasius fed different levels of a blend of botanical extracts during 8 weeks

PREVALENCE MONOGENEAN GILL

PARASITES

0

10

20

30

40

50

60

70

80

90

100

CONTROL APEX 0.5 kg/MT APEX 1 kg/MT

% O

F F

ISH

IN

FE

CT

ED

a a

b

Field trials with Gilthead seabream (Sparus aurata) in Greece

Objective: optimize formulation of APEX to reduce infestation

of seabream by monogenean gill parasites

Method: empiric testing in sea cages during 2010-2013 under

veterinary supervision at the farm

Results: application of APEX BRANCHIA may-july (challenging summer

period) resulted in 50-60% reduction of average monogenean

count per fish (light microscopic observation)

Nutriad’s innovative research on prevention of monogenean gill parasites

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Solution

• Reduce monogenean infestation throughout growout phase

• Preventive strategy:

• Starter feeds: 3 kg/ton

• Grower feeds: 2-3 kg/ton

APEX® BRANCHIA C

A synergistic formulation of natural compounds

with anti-parasitic action

•Medium chain fatty acids

•Botanical extracts

•Encapsulated essential oil complex

Conclusion

APEX® BRANCHIA C

• reduce the count of monogenean gill infestations on

productivity

• Preventive strategy:

• Starter feeds: 3 kg/ton

• Grower feeds: 2-3 kg/ton

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