This document discusses various disease conditions found in Mediterranean fish, with a focus on research conducted in Greece. It describes several viral, bacterial, and fungal pathogens that infect both marine and freshwater fish species. For viruses, it outlines nodavirus, lympocystis virus, and spring viraemia of carp. Key bacterial pathogens mentioned include Photobacterium damselae subsp. damselae, Vibrio anguillarum, Yersinia ruckeri, and Aeromonas salmonicida. Research from the University of Thessaly identified P. damselae in both wild and farmed fish in Argolikos Bay, Greece, demonstrating its ability to spread between populations.

1. UNIVERSITY OF THESSALYUNIVERSITY OF THESSALY
SCHOOL OF MEDICAL SCIENCESSCHOOL OF MEDICAL SCIENCES
FACULTY OF VETERINARY MEDICINEFACULTY OF VETERINARY MEDICINE
KARDITSA
LABORATOTY OF ICHTHYOLOGY , AQUATIC ANIMAL HEALTHLABORATOTY OF ICHTHYOLOGY , AQUATIC ANIMAL HEALTH && AQUACULTUREAQUACULTURE
Prof. Fotini Athanasopoulou DVMProf. Fotini Athanasopoulou DVM,, MScMSc,, PhDPhD,, MRCVSMRCVS
.
DISEASE CONDITIONS IN MEDITERRANEAN
FISH AND CURRENT RESEARCH IN
GREECE

2.
Viral conditions
VIRUS FISH SPECIES FISH SIZE MAIN CLINICAL
SIGNS
NODA VIRUS Dicentrarchus labrax (sea
bass)- M
Acipenser spp –FW
Mugil cephalus-FW
Young mainly
>150g
All sizes
Nervous signs, apathy,
bending of spine, eye lesions,
brain hemorrhages
LYMPHOCYSTIS Sparus aurata _M
Sparidae
young Skin granulomata
SPRING VIRAEMIA OF
CARP
Cyprinids 1-2 summers External and internal
hemorrhages

3. VIRUSES- MARINE FISH
LYMPHOCYSTIS
• Sea bream & other marine
species
•Summer outbreaks
•Granulomata on skin & gills
•Μacroscopic diagnosis
•Horizontal transmission

4. VIRUSES - MARINE FISH
Εικόνα 3: Ιοyενής εyκεφαλοπάθεια και αμφιβληστροειδοπάθεια σε ιχθύδια
λαβρακίου
NODA VIRUS
•Many marine species, sea bass,
•also in FW
•summer
•Nervous signs, distended swim
bladder,
•Histology, ELISA, IFAT, PCR
•Horizontal transmission
•High mortality

5. EPITHYLIOCYSTIS
(Chlamydia sp) RICKETSSIAS / RLO’s
•Many marine spp
•Spring and summer
•Lethargy, respiratory problems
•Μacroscopic examination
•Horizontal transmission?
μετάδοση ?
•High mortality in sea bream
•Many marine spp, sea bass in
Greece
•Winter
•Νervous signs no systemic
disease
•Histology
•Horizontal transmission?
• 20% mortality

6. Bacteria
Yersinia ruckeri
(ERM)
Salmonidae Adult and
young fish
Red mouth
Αeromonas spp
A. hydrophila
Α. salmonicida
Α. salmonicida ssp.nova
Salmonidae
FW
Cyprinids
FW
All
All
Hemorrhagic
septicemia
Cytophaga –like*
Flexibacter, Cytophaga, All
young and
adults
Skin lesions
mainly
FW fish

7. Bacteria
Vibrio (Listonella)
anguillarum
All marine
fish
All septicemia
All marine
fish
All
Pasteurella
(Photobacterium
piscicida)
Septicemia,
Granulomata
High mortality

8. ΒACTERIA – FW FISH
Yersinia ruckeri
Α. salmonicida
ssp.nova
Α. salmonicida Furunculosis

9. Βacteria
Bacterium
Fish
species
Fish size Clinical
signs
Mycobacterium
spp.
All Older fish
Internal &
external
swellings,
granulomata,
ulcers. Ascites,
exophthalus
Nocardia sp. All Older fish,
broodstock
Internal &
external
swellings,
granulomata,
ulcers. Ascites,
exophthalus
Streptococcus sp.
Gram+
All mainly
trout
All septicemia
Renebacterium sp.
Gram+
Salmonid
ae
Adults Abscesses in
kidneys,
swellings

10. BACTERIA- FW FISH
Renebacterium salmoninarum
Myxobacteria

11.
Agent Fish
species
Fish size Clinical
signs
Saprolegnia sp. ALL ALL Skin lesions
Branchiomyces CYPRINID
S
ALL Gill lesions
Ichthyophonus
hoferi
Salmonidae
Marine fish
young Systematic
disease
Exophthiala sp Salmonidae ALL Lesiona in
kidneys, spleen
Αphanomyces
astaci
Decapoda,
Astacus
spp.
- Necrosis
Fungal diseases

12. FUNGHI
Ichthyophonus hoferi
Saprolegnia spp

13. BACTERIOLOGICAL STUDY OFBACTERIOLOGICAL STUDY OF
CULTURED AND WILD FISH INCULTURED AND WILD FISH IN
ARGOLIKOS BAY, GREECEARGOLIKOS BAY, GREECE
Passas Ν.1
, Yiagnisi Μ.1,2
, Bithava Κ.1
,
Vagianou Βαγιάνου S.1
, Τzironi Ε.1
&
Αthanassopoulou F.1
1
Laboratory of Ichthyology & Aquatic animal Health Faculty of
Veterinary Medicine, University of Thessaly
2

14. AimAim
In this study we investigated the possibility of
finding simultaneously the same bacterial isolates
in both cultured and wild fish around sea cages in
Greece

15. Three seasonal samplings of diseased cultured
fish (Sparus aurata, Dicentrarchus labrax) from 3
farms in Argolikos Bay.
Simultaneoysly, samples of wild fish were
examined, near the cages (200-500 m) were
problems were present.

16. Wild fishWild fish
Είδη άγριων ψαριών Απομονωθέντα
βακτηρίδια
Boops boops Ph.damselae
ssp.damselae
Trachurus trachurus Ph.damselae
ssp.damselae,
V.vulnificus
Trachurus
mediterranei
Ph.damselae
ssp.damselae
Boops boops Ph.damselae
ssp.damselae,V.harveyi

17. SpringSpring

18. SummerSummer

19. AutumnAutumn

20. ResultsResults
Photobacterium damselae subsp. damselae was widely present in
the bay and more often isolated from wild fish.
It was isolated in all samplings: spring in wild fish, summer &
autumn in cultured & wild fish.
In cultured fish the following bacteria were also isolated: Vibrio
alginolyticus, V. harveyi, V. parahaemolyticus, V. aestuarinus, V.
tubiashii και V. splendidus II.

21. Photobacterium damselaePhotobacterium damselae subspsubsp..
damselaedamselae
Present in water & can be transmitted through
water
Previously described as a new Vibrio pathogen
causing lesions to Chromis punctipinnis (Love et
al. 1981).
Enters through skin
Includes isolates causing skin problems and
hemorrhagic septicemia in various marine fish sp.
Is a pathogen also of mammals and humans
(damselae).

22. Photobacterium damselaePhotobacterium damselae subsp.subsp.
damselaedamselae
Fish pathogens: Photobacterium damselae
subsp. piscicida previously Pasteurella piscicida.
Only Ph. damselae is pathogen for humans.

23. ConclusionsConclusions
Wild fish can be carriers of P.
damselae subsp. damselae.
Vibrio spp. such as V. vulnificus
and V. harveyi can be isolated from
wild fish

24. VIBRIOSVIBRIOS
ΓΕΝΙΚΑ ΠΕΡΙ VIBRIO spp
 Το γένος Vibrio περιλαμβάνει Gram- , οξειδάση θετικούς (εκτός από δύο
είδη) και αναερόβιους βακίλους που ανήκουν στην οικογένεια
Vibrionaceae.
 Eίναι κοινά βακτήρια του νερού σε θαλάσσια και υφάλμυρα
οικοσυστήματα
 Τουλάχιστον 12 είδη Vibrio spp είναι παθογόνα στον άνθρωπο, 10 από τα
οποία συνδέονται με τροφογενείς λοιμώξεις. (Vibrio parahaemolyticus ,
Vibrio vulnificus, Vibrio alginolyticus)
 Προκαλούν τρία κυρίως σύνδρομα: Γαστοεντερίτιδα, μολύνσεις
τραυμάτων και σηψαιμία

25. Agent:
Vibrio anguillarum (Listonella anguillarum).
10 serotypes:
 01 serotype commonly in mediterranean fish.
02 in eels
03 in larvae in France.
Listonella anguillarum

26.  In both cultured and wild fish –epizootics (1817,
1987 and after).
 In many fish species
 Problem in farms before vaccine use
 Still a problem in «new» cultured fish (halibut, cod
- Bergh et al. 2001)
 In mediterranean fish sea bass (Dicentrarchus
labrax) is the most sensitive
 Related infections in molluscs and bivalves and
crustaceans.
Sensitive fish species:

27. Temperature and infectionTemperature and infection
 Autumn and spring ( from 20°C to 15°C & vice versa)
 Accompanied by high daily changes.
 Recently in Greece the disease appears also in winter at T< 15°C.

28. Clinical signsClinical signs ::
 Vibriosis is a classical gram negative haemorrhagic septicaemia. The
outstanding feature of clinical vibriosis is the level of anaemia.
Typical signs are red spots on the ventral and lateral areas of the fish,
and swollen and dark skin lesions that ulcerate, releasing a bloody
exudate.
 Hyperacute: no clinical signs except for anorexia and dark colour.
 Acute form: Externally: erythema on skin exophthamos, Sometimes
also ulcers. Internally: hemorrhagic septicemia, spleen distension ,
hyperemic intestine

29. Furunculosis in sea bass D. labrax

30. Μ.Μ. yiagnisiyiagnisi 1,21,2
, Κ., Κ. BitchavaBitchava22
, , Α, , Αggelidesggelides PP..33
,, VatsosVatsos Ι.Ν.Ι.Ν.33
καικαι
ΑΑthanassopoulouthanassopoulou FF22
..
11
Laboratory of nutrition and Fish Diseases, Inst. Of Aquaculture, NCMR,, Hellinikon, Greece
2
Laboratory of Ichthyology & Aquatic Animal Health,,Faculty of Veterinary Medicine, University of Thessaly
3
Laboratory of Ichthyology and Fish Diseases, School of Veterinary Medicine, University of Thessaloniki
ISOLATION AND IDENTIFICATIONISOLATION AND IDENTIFICATION
OFOF Vibrio harveyiVibrio harveyi IN CULTURED MARINEIN CULTURED MARINE
FISH IN GREECEFISH IN GREECE

31. Το Vibrio harveyi είναι Gram-ve bacterium common
in the sea . Previously called Achromobacter harveyi.
Pathogen of many invertebrates esp. of the family
Penaeidae.
Part of natural enteric fauna of marine organisms.
Reported as a common opportunist pathogen in many
marine fish.
Vibrio harveyiVibrio harveyi

32.  Vibrio harveyi isolated from internal organs of diseased fish sea bass
(Dicentrarchus labrax) and sea bream (Sparus aurata) σε εκτροφές της Ελλάδας .
Related to management stress or parasitic infections.
Infected sea bream showed anorexia, abnormal swimming, dark colour, scale loss,
skin ulcers.
 Infected sea bass showed skin hemorrhages and exophthalmia.
Both fish species in the summer and autumn there was a peak of signs that were
related to this bacterium.
Sea bass was more sensitive with mortalities hoigher than 50%.
Vibrio harveyiVibrio harveyi in our researchin our research

33. Isolation was achieved by biochemical and molecular
methods. Sequence was very similar to Vibrio alginolyticus.
MicroSeq 500 16S rDNA Bacterial Identification kit (Applied
Biosystems) and BLAST data were used.
Isolation & identificationIsolation & identification

40. 
Από τον Απρίλιο τουΑπό τον Απρίλιο του 20062006, Στην Κτηνιατρική Σχολή του ΑΠΘ, λειτουργεί μια Τράπεζα, Στην Κτηνιατρική Σχολή του ΑΠΘ, λειτουργεί μια Τράπεζα
αναφοράς παθογόνων βακτηριδίων, απομονωμένα από εκτρεφόμενα ψάρια της Ελλάδας.αναφοράς παθογόνων βακτηριδίων, απομονωμένα από εκτρεφόμενα ψάρια της Ελλάδας.
Στο πρόγραμμα αυτό συμμετέχουν επίσης:Στο πρόγραμμα αυτό συμμετέχουν επίσης:
Το εργαστήριο Ιχθυολογίας, του Τμήματος Κτηνιατρικής, του πανεπιστημίου της ΘεσσαλίαςΤο εργαστήριο Ιχθυολογίας, του Τμήματος Κτηνιατρικής, του πανεπιστημίου της Θεσσαλίας
Το Ινστιτούτο Υδατοκαλλιεργειών, του Ελληνικού Κέντρου Θαλασσίων ΕρευνώνΤο Ινστιτούτο Υδατοκαλλιεργειών, του Ελληνικού Κέντρου Θαλασσίων Ερευνών
(ΕΛ.ΚΕ.Θ.Ε), της Αθήνας(ΕΛ.ΚΕ.Θ.Ε), της Αθήνας
Συντονιστής προγράμματοςΣυντονιστής προγράμματος ::Παναγιώτης ΑγγελίδηςΠαναγιώτης Αγγελίδης ,,
Επίκουρος καθηγητής Κτηνιατρικής Σχολής ΑΠΘ,Επίκουρος καθηγητής Κτηνιατρικής Σχολής ΑΠΘ,
Email:Email: panangel@vet.auth.grpanangel@vet.auth.gr
Το πρόγραμμα χρηματοδοτείται από το Υπουργείο Αγροτικής Ανάπτυξης & ΤροφίμωνΤο πρόγραμμα χρηματοδοτείται από το Υπουργείο Αγροτικής Ανάπτυξης & Τροφίμων
Γεν. Δ/ση ΑλιείαςΓεν. Δ/ση Αλιείας ,, Δ/ση Αλιευτικών Εφαρμογών , ΕΠΑΛΔ/ση Αλιευτικών Εφαρμογών , ΕΠΑΛ 2000 – 2006,2000 – 2006, ΜέτροΜέτρο 4.64.6
GreekGreek
AquacultureAquaculture
BacteriaBacteria
CollectionCollection

41. Purpose of this program:Purpose of this program:
Isolation and identification of bacterial pathogens of cultured fish in Greece
with microbiological, biochemical and molecular methods.
Pathogenicity tests of isolates.
Hisopathological study of diseased fish.
Preservation of isolates for future use & research (vaccines, auto vaccines).
Information to anybody involved.
Cooperation with other data bases abroad.

42. Στάδια
 Συλλογή ψαριών, απομόνωση και ταυτοποίηση
βακτηριδιακών στελεχών
 Ιστολογική εξέταση
 Μοριακή ταυτοποίηση
 Συλλογή των απομονωθέντων βακτηριδίων στους
-80ο
C
This data bas follows the directions of the World
Federation for Culture Collection

43. Macroscopic lesions and bacteria isolated from cultured
fish
Fish species Isolated bacteriaα Macroscopic lesions
Dicentrarchus labrax Listonella anguillarum (12) Αιμορραγίες γύρω από τα βραγχιακά
επικαλύμματα, τα πτερύγια, την έδρα, ασκίτης,
συμφόρηση εσωτερικών οργάνων
Vibrio alginolyticus (2) Αιμορραγίες γύρω από την έδρα, πληγές,
σπληνομεγαλία
Sparus aurata L. anguillarum (1) Αιμορραγίες γύρω από την έδρα, ασκίτης,
αιμορραγίες στο ήπαρ
V. alginolyticus (5) Αιμορραγίες γύρω από τα βραγχιακά
επικαλύμματα και τα πτερύγια
Photobacterium damsela ssp piscicida (2) Συμφόρηση εσωτερικών οργάνων, όζοι πάνω
στα εσωτερικά όργανα, κυρίως στον σπλήνα
L. metsscnikovii (1) Δεν παρατηρήθηκαν βλάβες
Unidentified coccus (1) Αιμορραγίες στο λίπος γύρω από τα εσωτερικά
όργανα
Anguilla anguilla Aeromonas spp. (3) Αιμορραγίες στα βραγχιακά επικαλύμματα ,
δερματικά έλκη
Oncorhynchus mykiss Aeromonas spp. (1) Αιμορραγίες στα βραγχιακά επικαλύμματα, τα
πτερύγια, σπληνομεγαλία, ηπατομεγαλία
Pagrus pagrus L. anguillarum (1) Αιμορραγίες στα βραγχιακά επικαλύμματα
Carassius auratus A. hydrophila (1) Αιμορραγίες γύρω από τους οφθαλμούς και την
βάση των πτερυγίων, ασκίτης, σπληνομεγαλία,
διόγκωση χοληδόχου κύστης
Cyprinus carpio Aeromonas spp. (not A. salmonicida) (1) Ασκίτης, σπληνομεγαλία, ηπατομεγαλία
Pagellus erythrinus -** Ασκίτης , καχεξία
Carassius auratus gibelio A. sombria (1) Αιμορραγίες γύρω από τα βραγχιακά , στη βάση
των πτερυγίων και το στόμα, σπληνομεγαλία,
διόγκωση χοληδόχου κύστης λευκόφαιο ήπαρ

44. Number of examined fish andtheir isolatesNumber of examined fish andtheir isolates
Fish species No of cases Total number of
examined fish
Isolated bacteria*
Dicentrarchus labrax 16 129 Listonella anguillarum (12)
Vibrio alginolyticus (2)
Sparus aurata 14 176 L. anguillarum (1)
V. alginolyticus (5)
Photobacterium damsela ssp piscicida (2)
L. metsscnikovii (1)
Αταυτοποίητος κόκκος (1)
Anguilla anguilla 4 13 Aeromonas spp. (3)
Oncorhynchus mykiss 1 1 Aeromonas spp. (1)
Pagrus pagrus 1 4 L. anguillarum (1)
Carassius auratus 2 6 A. hydrophila (1)
Cyprinus carpio 1 4 Aeromonas spp. (όχι A. salmonicida) (1)
Pagellus erythrinus 1 3 -**
Carassius auratus gibelio 1 5 A. sombria (1)
Solea solea 1 10 V. alginolyticus (1)
Diplodus puntazzo 1 1 V. alginolyticus (1)
* () no of cases from which pathogen was isolated **Σημείωση: no bacterial isolated

45. Αscites- V. alginolyticus.
Spleen
smears
Giemsa X300
ΝΝecrotic lesion and granulomaecrotic lesion and granuloma
formation in sea bream kidneys,formation in sea bream kidneys,
H&EH&E

46. Enteritis in sea bass swelling ofEnteritis in sea bass swelling of
entericenteric.. H&EH&E..
Endocarditis lesion in sea bassEndocarditis lesion in sea bass ..
H&E.H&E.
ΝΝecrotic lesions and granulomata formationecrotic lesions and granulomata formation
in sea bream spleen.H&E.in sea bream spleen.H&E.

47. PARASITESPARASITES

48. ICH CRYPTOCARYON sp
•All FW & tropical fish
•Any age
•T 3-20ο
C
•Skin lesions, dyspnoia
•Direct observation -2 stages
in gills and tanks
•All Marine fish
•Any age
•T >20ο
C
•Skin and gill lesions
•Direct observation -2 stages
in gills and tanks

49. METACERCAREA
NEMATODA
Anguillicola crassus
Diplostomum spathaceum
•Many FW spp,
• esp. Salminidae
•T 3-20ο
C
•Cataract, blindness
•Direct observation
•Indirect life cycle
•In Swim bladder of eels
Also in Salmonidae
•Immunosupression,
abnormal swimming
•Direct observation
•Indirect life cycle

50. TREMATODA ARTHROPODA, COPEPODA
Microcotyle sp.
Lernathropus kroyeri.
Ceratothoa oestroides

51. Microcotyle sp.

52. PARASITES- PROTOZOAPARASITES- PROTOZOA
TRICHODINA
CHILLODONELLA sp.
•Stress related
•Any species, any age
•Direct diagnosis in skin & gill
smears
OODINIUM sp. •Marine spp
•>20C
•Skin lesions
•Direct diagnosis in skin
& gill smears
•High mortality
•All FW fish esp.
mullets
•Any age at high
temperature
•Skin lesions
•Direct diagnosis in skin &
gill smears
•Low mortality

53. Enteromyxum (Myxidium) leei
•Internal organs esp gall bladder
•Microscopic direct diagnosis
•Low mortality
Ceratomyxa sp.
ΜΥΧΟSPORIDA
•Diplodus puntazzo, sea bream, Pagrus major,
P. pagrus
•T >20ο
C
•Internal organs. Cachexia, serious histological
lesions in intestine
•Direct life cycle
•High mortality

54. Polysporoplasma sparis
Kudoa sp.
Μιcrosporida
•In renal tubules
•Any age
•Direct diagnosis in smears of
kidneys
•Low mortality
In musculature μύς of marine fish
•Indirect life cycle???

55. Polysporoplasma sparis

56. CONDITIOΝ FISH
SPECIES
FISH SIZE CLINICAL
SIGNS
Gill disease ALL ALL Respiratory
Gas babble
disease
ALL ALL Bubbles in
skin, blood
vessels
Fat degeneration
/necrosis
ALL /
(TROUT)
ALL Discolourizati
on of liver
Systemic
granulomatosis
Marine sea
bream,
P.puntazzo
cages
Swelling of
kidneys, int.
organs
/granulomata
Winter syndrom Sea
bream
Cages Ascites, gill
necrosis,
hyperenia of
intestine
Non infectious diseases

57. Fat degeneration of
liver
Dietory Cataract
Gas bubble disease
Winter syndromeSystematic granulomatosis