Basidiobolus spp

From Fish
Basidiobolus spp fungal spores in sloughed skin

Basidiobolus ranarum, a widespread saprophytic fungus, causes xygomycosis, a fungal disease of the skin and subcutaneous tissues of fish.

The causative agent is common in decaying vegetable matter, and the gastrointestinal tracts of freshwater fish[1].

Basidiobolus spp are members of the family Entomophthoraceae[2]. When cultured, it is easily identified based on its distinctive ‘‘beaked’’ zygospores and Streptomyces-like odor[3].

Clinical signs

Fungal spores cause vegetative lesions on the skin and fins of both aquarium and wild fish, resulting in systemic fungal disease and superficial skin infections such as fin rot.


Diagnosis is based on identification of fungal hyphae and spores. Isolation of the same fungal species from multiple consecutive specimens and demonstration of the isolate’s capability to grow are required for assessing the infection[4]. In vitro susceptibility testing, as with other fungi, is not reliable in guiding therapeutic decisions.


Potassium iodide is the drug of choice, and the response to it may be of diagnostic help. Several other drugs including ketoconazole, trimethoprim, sulfamethoxazole, amphotericin, itraconazole and fluconazole have also been used[5].


  1. Gugnani, HC (1999) A review of zygomycosis due to Basidiobolus ranarum.. Eur J Epidemiol 15(10):923-929
  2. Coremans-Pelseneer, J. (1973) Isolation of Basidiobolus meristosporus from natural sources. Mycopathologia et Mycologia applicata 49:173–176
  3. Drechsler, C. (1956) Supplementary developmental stages of Basidiobolus ranarum and Basidiobolus haptosporus. Mycologia 48:655–676
  4. Posteraro P, Francis C, Didona B, et al (2003) Persistent subcutaneous scedosporium apiospermum infection. Eur J Dermatol 13:603-5
  5. Sugar AM. (2000) Agents of mucormycosis and related species. In: Mandell GL, Bennett GE, Dolin R editors, Mandell, Douglas, and Bennett`s, eds. Principles and Practice of Infectious Diseases, 5thed. NewYork: Churchill: Livingstone, pp:2685-2695