Swim bladder mycosis in pretty tetra (Hemigrammus pulcher) caused by Exophiala pisciphila and Phaeophleospora hymenocallidicola, and experimental verification of pathogenicity

Abstract

Spontaneous invasive and chronic disseminated mycosis affected Hemigrammus pulcher kept in a public aquarium, and infection was manifested by inappetence, exophthalmia, erratic swimming, eroded scales, anaemia of the gills and abdominal distension. Internally, there was a grossly swollen swim bladder with a thickened wall filled with a dark mass. The body cavities contained a clear, light amber fluid and a swollen intestine which was full of a watery fluid containing small gas bubbles. Histopathology revealed a granulomatous inflammatory response with fungal hyphae in the lumen and wall of the swim bladder, hepatopancreas, spleen and kidneys with signs of nephrohydrosis. Exophiala pisciphila and Phaeophleospora hymenocallidicola were isolated from the swim bladder, abdominal cavity and gastrointestinal tract. The exogenous source of infection was probably the ample wooden decoration and plants inside the aquarium. Koch's postulates were fulfilled by re-isolation of both fungal species from fish artificially infected under laboratory conditions. As P. hymenocallidicola is less capable of defence against phagocytosis, E. pisciphila probably played a major role. Severe clinical manifestations with 100% mortality developed in two fish species infected by E. pisciphila. A significant increase in the plasma levels of amino acids was observed as a result of the activation of proteolysis.

A visceral mycosis in farmed rainbow trout (Oncorhynchus mykiss) caused by Neopyrenochaeta submersa

“…Previously reported fish infections were mostly attributed to coelomycete genus Phoma and reviewed by Řehulka et al [ 7 ]. Other coelomycete genera are rarely reported as fish pathogens [ 8 ]. Until now, only single study reported genus Neopyrenochaeta as animal pathogen, namely, N. acicola has been reported in fish [ 6 ].…”

“…Pyrenochaeta acicola ) [ 6 ]. Other cases of infection in fish due to coelomycetous fungi are mostly restricted to the genera Phoma or Phaeophleospora [ 7 , 8 ].…”

Phaeohyphomycosis due to Exophiala in Aquarium-Housed Lumpfish (Cyclopterus lumpus): Clinical Diagnosis and Description

“…angulospora complex' [9,10]. Exophiala salmonis infections have been reported in Atlantic salmon (Salmo salar L.) and smooth dogfish (Mustelus canis) [11][12][13], E. pisciphila in channel catfish (Ictalurus punctatus), Atlantic salmon (Salmo salar L.), cardinal tetra (Paracheirodon axelrodi), and pretty tetra (Hemigrammus pulcher) [14][15][16][17], E. xenobiotica in striped jack (Pseudocaranx dentex) and Queensland grouper (Epinephelus lanceolatus) [18,19], and E. aquamarina in weedy (Phyllopteryx taeniolatus) and leafy seadragons (Phycodurus eques), little tunnyfish (Euthynnus alletteratus), winter flounder (Pseudopleuronectes americanus), sharphead flyingfish (Hirundichthys oxycephalus), and lumpfish (Cyclopterus lumpus) [9,10,20]. Exophiala angulospora inhabits cold waters worldwide, is considered an opportunistic pathogen with invasive potential and dissemination in cold-blooded vertebrates, and it has been reported in aquarium-housed weedy seadragons (Phyllopteryx taeniolatus), Atlantic halibut (Hippoglossus hippoglossus), farmed Atlantic cod (Gadus morhua), and farmed Japanese flounder (Paralichthys olivaceus) [9,10,[21][22][23].…”