Barley Straw and Fungus

It is a little known fact that the use of barley straw may suppress the growth of fungi. In a study by Cooper and colleges three subspecies of Saprolegnia (S. diclina, S ferox and S. parasitica) were identified to inhibit the growth of the mycelium of these common fish fungi. It certainly warrants further investigation and testing.

Important is to note that this growth suppression was witnessed for up to 6 months after application and depended on the species of fungus.

Since this effect is noticed at the same type of concentration as used in general for algalstatic barley straw application, it might be a good practice to apply it as a prophylactic against such invasions.

Use of the KoiNet products BioClear (standard matured barley straw), BioClear-RS (inoculated, aged straw) can be considered

Servaas de Kock


Source: Cooper, A.J., Pilinger, J.M. and Ridge, I. (1997). Barley straw inhibits growth of some aquatic saprolegniceous fungi. Aquaculture. 156. 1-2. 157-163


Barley straw rotting in water under aerobic conditions controls the growth of both algal and cyanobacterial species and is exploited as a method to control nuisance algae. We report here the effect of anti-algal straw on isolates of an aquatic fungus that comprises a significant component of the freshwater aquatic ecosystem and causes a major fungal disease in fish and other aquatic animals. In a laboratory bioassay, straw, at dose rates comparable to those which inhibit algal growth, stopped the mycelial growth of isolates of two species of Saprolegnia, S. parasitica and S. diclina; S. ferax was less inhibited. Inhibition in the laboratory bioassay was also recorded at the lower dose rate at which straw is widely used in environmental algal control programmes. We suggest that straw may ameliorate symptoms of saprolegniasis in fish, but it is not clear whether straw can prevent the rapid spread of the fungus in hatcheries.

Ameliorate = make (something bad or unsatisfactory) better.

Read also HERE about Barley Straw:

CLICK HERE to find out where to purchase