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7/28/2019 Non-lethal infestation by praniza larvae(Crustacea, Isopoda, Gnathiidae)in a Mediterranean marine ornamental aq
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Arbuatti Alessio1, Della Salda Leonardo2, Romanucci Mariarita21Veterinary practitioner, Mozzagrogna (Chieti, Italy)
2Faculty of Veterinary Medicine, University of Teramo, Italy
X National Meeting of Italian Association of Veterinary Pathology (AIPVet), Giulianova Lido (Teramo, Italy), 29-31 May
IntroductionOrnamental fish are the most popular pets in Italy (about 60 millions of bred specimens), since aquarium management appears to be a particularly loved hobby that supports a million
arketing. In addition to home aquariums, there are numerous public and private aquariums open to the public and based on the modern concept of edutainment, i.e. education + entertespite the modern veterinary, biological and technological knowledge have improved animal welfare in properly managed aquariums, 90% of captive-bred fish deaths are due to various
stressors originating from an improper management of the aquarium system.
Results
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Materials and MethodsThe involved aquarium was composed of a pentagonal, 500 L tank (Fig.1), activerom 3 years, equipped with a filtration and recirculation system (Fig.2) locatedwithin the below sump, containing a skimmer Lg.500, a biological filter and ahiller Resun 500. Partial water changes (20%) were performed every 3 weeksusing natural marine water caught at a depth of 80-90 cm. The hosted faunancluded: 1 moray eel (Muraena helena, Linnaeus 1758) 80 cm in length, 1 duskyouper (Epinephelus marginatus, Lowe 1834) 38 cm in length, some specimens of
genus Blennius, small crustaceans of genus Palaemonandmarine invertebratesuch as Actinia equina(Linnaeus, 1758) and Anemoniasulcata(Pennant, 1777).eding was performed every 2 days, periodically using even small, live or freshlycaught fish such as saddled seabreams (Oblada melanura) (Linnaeus, 1758),
wrasses (Symphodus spp.) and small mullets (Mugil spp.).rst parasite detection concerned the observation of a single specimen attachedto the perioral area of the moray (Fig.4); the number of observable parasites
progressively increased, showing variable size (from 1mm to 2-3mm) andlocalization on fish body (Fig.3-5). Some parasitic bodies were caught by
piration for direct observation, identification and iconographic documentation.
The infestation lasted formonths: most of parasitic battached to the eye rims o
(Fig.3,5) and the perioral zo(Fig.4), while no parasite
observed on blennies and crAffected fish did not showappetite loss; however, theinduced discomfort was sugtheir frequent rubbing on
Parasites were toughly attachost skin and constantly swhitish colour during the
artificial lighting.As a resultdetachment, mild lesions repabrasions and areas of dep
were observed on fish skiParasitic bodies were iden
praniza larvae of Gnat(Crustacea, Isopoda)(
References Becker JH, Grutter AS (2004) Coral Reefs23: 515-520. Davies AJ, Smit NJ (2001) Folia Parasitol48: 169177. Diniz et al. (2008) An Acad Bras Cienc80: 657-664. Marino et al. (2004) Dis Aquat Org59: 43-47. Noga EJ (2010) Fish Disease: Diagnosis and Treatment. 2nd Edit
Blackwell. Smit NJ, Davies AJ (2004) Adv Parasitol58: 289-391.
Fig. 1 Fig. 2
Non-lethal infestation by praniza larvae(Crustacea, Isopoda, Gnathiidae)
in a Mediterranean marine ornamental aquarium
ig. 3
g. 4
Discussion Gnathids (Isopoda, fam. Gnathiidae) are crustacean ectoparasitesof a number of both teleost and elasmobranch species worldwide. To date,however, there are no literature reports of Muraena helenainfestation. The biological cycle, which lasts about 62 days, is composed by aee-living, usually benthonic, adult stage and a complex larval phase, consisting of 3 unfed (zuphea) stages and three fully fed (praniza) stages.
Praniza larvae are usually found attached on skin, buccal cavity or gills, and feed with blood and/or lymph (Smit and Davies, 2004).Their pathogeniccapability is related to anaemia due to haematophagia, tissue damage predisposing to electrolyte imbalances or secondary
infections (Marino et al., 2004), and a potential vector role of protozoan parasites such as Haemogregarinaspp.(Davies and Smit, 2001).However, observable lesions are variable, being sometimes irrelevant, as in our case, or severe, with high mortality (Diniz et al., 2008).
Gnathid infestation may represent a serious problem for public aquariums with direct seawater acquisition and the solution is represented byltration treatments with UV and ozone generators of seawater collected in storage tanks. For domestic aquariums, the use of osmotic waterconstituted with salts sold in special stores is recommended. Introduction of correctly quarantined new fish is in any case a fundamental stepto prevent parasite infestations. As regards the correct therapy, it must also include a treatment of the aquarium environment housing the
hardly visible adult stages, which can be performed by pharmacological treatments and biological control (Noga, 2010).our case, the addition of water from kalkwasser system to increase pH may have contributed to parasite disappearance. However, an abrupt
ncrease in water pH, able to cause parasite death, would have probably caused some damages in the other crustaceans and invertebrates, asell as fish, housed within the tank, which did not show any alteration. More important for therapeutic purposes appears to be the introduction "cleaner shrimps (Fig.8,9), which feed on fish by removing small flaps of skin, food debris and parasites. Some species of shrimp are knownto remove Gnathids from tropical fish skin (Becker and Grutter, 2004) and a similar event may be occurred in our case, although a direct
contact between shrimps and parasitized fish was not observed during daylight hours.The efficacy of the treatment may be particularly assumed by the absence of infestation recurrence during the following years, which
suggests the elimination of both larval and adult stages.
Fig. 5presumably belonging to the genus Gnathia,
which includes the most of known species. Thegradual disappearance of infestation, without
relapses, was obtained as a result of one or bothof the actions carried out by the aquarist. The
first one consisted of adding water from akalkwasser system in order to increase pH. Thesecond intervention, likely the most effectivefor therapeutic purposes, was represented by
the introduction of 30 specimens of wildLysmata seticaudata(Risso, 1816), the so-called
Mediterranean "cleaner shrimp"(Fig.8).
Fig. 6
Fig. 7: Gnathiid praniza larva(about 2.5mm in length).
Fig. 9: Some Lysmata seticaudatain cleaning phasemoray muzzle (By courtesy of Protected Marine A
Portofino (Italy) A. Serafini photo).
AcknowledgementsWe would like to thank Livio Macera for kind cooper
