a b s t r a c t
Peppermint (Mentha piperita L.) is a very popular herb. While numerous effects have been described in
mammals, its effects on fish have received so far limited attention. The effects of dietary administration
of peppermint on fry Caspian white fish (Rutilus frisii kutum) were studied. Fish were divided into 4
groups before being fed diets supplemented with 0% (control), 1%, 2% and 3% of peppermint extracts for 8
weeks. Dose-dependent increases of growth parameters (WG and SGR), mucus skin (protein concentration,
alkaline phosphatase and antimicrobial activity) and seric (lysozyme and IgM) and blood leucocyte
respiratory burst activities and different hematological parameters (number of red and white
cells, seric hemoglobin and hematocrit content) were recorded in fry fish fed supplemented diets.
However, the dietary peppermint supplements have different effects on the number of blood leucocytes
depending on the leucocyte cell type. While no significant differences were observed in the number of
blood monocytes and eosinophils, the number of neutrophils and lymphocytes was increased and
decreased, respectively, on fish fed peppermint enriched diets, respect to the values found in control fish.
Present results corroborate that dietary administration of peppermint promotes growth performance
and increases the main hematological and immune humoral (both mucosal and systemic) parameters of
fry Caspian white fish. This study may provide new applications of peppermint and, at the same time,
promote rational development and utilization of peppermint resources.