Scientific classification e
Kingdom: Chromalveolata
Phylum: Heterokontophyta
Class: Oomycota
Order: Saprolegniales
Family: Saprolegniaceae
Genus: Saprolegnia

S. australis
S. ferax
S. declina
S. longicaulis
S. mixta
S. parasitica
S. sporangium
S. variabilis

Saprolegnia is a genus of freshwater mould often called a "cotton mould" because of the characteristic white or grey fibrous patches it forms. Current taxonomy puts Saprolegnia as a genus of the heterokonts in the order Saprolegniales.



Saprolegnia, like most water moulds, is both a saprotroph and necrotroph. Typically feeding on waste from fish or other dead cells, they will also take advantage of creatures that have been injured or compromised eggs. When they inhabit a live animal, they exhibit as a fungal infection known as mycoses.

Saprolegnia is tolerant to a wide range of temperature, 3°C to 33°C, but is more prevalent in lower temperatures. While it is found most frequently in freshwater, it will also tolerate brackish water and even moist soil.

Saprolegnia filaments (hyphae) are long with rounded ends, containing the zoospores. Saprolegnia generally travels in colonies consisting of one or more species. They first form a mass of individual hyphae. When the mass of hyphae grows large enough in size to be seen without use of a microscope, it can be called a mycelium. Colonies are generally white in color, though they may turn grey under the precesence of bacteria or other debris which has become caught in the fibrous mass.


It has a diploid life cycle which includes both sexual and asexual reproduction. In the asexual phase, a spore of Saprolegnia releases zoospores. Within a few minutes, this zoospore will encyst, germinate and release another zoospore. This second zoospore has a longer cycle during which most dispersal happens; it will continue to encyst and release a new spore in a process called polyplanetism until it finds a suitable substrate. When a suitable medium is located, the hairs surrounding the spore will lock onto the substrate so that the sexual reproduction phase can start. It is also during this stage of polyplanetism that the Saprolegnia are capable of causing infection; the most pathogenic species have tiny hooks at the end of their hairs to enhance their infectious ability.

Once firmly attached, sexual reproduction begins with the production of male and female gametangium, antheridia and oogonium respectively. These unite and fuse together via fertilization tubes. The zygote produced is named an oospore.

Characteristics of Infection

Saprolegnia is generally a secondary pathogen, though in the right circumstances, it can act as primary. It most frequently targets fish, both in the wild and in tank environments. Through cellular necrosis and other epidermal damage, Saprolegnia will spread across the surface of its host as a cotton-like film. Though it often stays in the epidermal layers, the mould does not appear to be tissue specific. A Saprolegnia infection is usually fatal, eventually causing haemodilution, though the time to death varies depending on the initial site of the infection, rate of growth and the ability of the organism to withstand the stress of the infection.

The extensive mortalities of salmon and migratory trout in the rivers of western Europe in the 1970's and 1980's in the UDN outbreak were probably almost all ultimately caused by the secondary Saprolegnia infections.

Historial evidence suggest the Saprolegnia species affecting Australian freshwater fish may be an introduced strain, imported in the 1800s with exotic fish species.


  • Bruno, D.W., and Wood, B.P. (1994). Saprolegnia and other Oomycetes. CABI Publishing
  • Meyer, F.P. (1991). Aquaculture disease and health management.

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  • Saprolegnia — Saltar a navegación, búsqueda ? Saprolegnia Clasificación científica Reino: Protista Filo …   Wikipedia Español

  • Saprolegnia — Saprolegnia …   Wikipédia en Français

  • Saprolegnĭa — Nees ab Es., Gattung der Saprolegniazeen, auf faulenden Pflanzen oder Tierkörpern im Wasser wachsende Pilze, deren Schwärmsporen zunächst mit zwei endständigen Cilien aus den Zoosporangien austreten, dann zur Ruhe kommen und sich mit einer… …   Meyers Großes Konversations-Lexikon

  • Saprolegnia — Saprolegnĭa N. ab Es., Pilzgattg. der Saprolegniazeen, saprophytische und parasitische Pilze, die im Wasser auf Tieren und Pflanzen leben und sie mit einem weißen Filz überziehen, z.B. S. monoĭca Pringsh. [Abb. 1596: Rasen auf einer ins Wasser… …   Kleines Konversations-Lexikon

  • saprolegnia — ● saprolegnia nom masculin Champignon siphomycète aquatique, dont certaines espèces forment sur les écailles des poissons une sorte de barbe de couleur blanche …   Encyclopédie Universelle

  • Saprolegnia — Wasserschimmel Systematik Domäne: Eukaryoten (Eucaryota) Reich: Stramenopile (Stramenopila) Abteilung: Eipilze Ordnung …   Deutsch Wikipedia

  • Saprolegnia — Saprolegnia …   Wikipédia en Français

  • Saprolegnia — noun aquatic fungi growing chiefly on plant debris and animal remains • Syn: ↑genus Saprolegnia • Hypernyms: ↑fungus genus • Member Holonyms: ↑Saprolegniales, ↑order Saprolegniales • Member …   Useful english dictionary

  • saprolegnia — /sæproʊˈlɛgniə/ (say saproh legneeuh) noun any of a group of aquatic fungi of the genus Saprolegnia, which feed on animal matter including diseased fish …  

  • Saprolegnia ferax — noun a fungus that attacks living fish and tadpoles and spawn causing white fungus disease: a coating of white hyphae on especially peripheral parts (as fins) • Syn: ↑white fungus • Hypernyms: ↑fungus • Member Holonyms: ↑Saprolegnia, ↑genus… …   Useful english dictionary

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