BIOLOGICAL STUDIES ON KANNUME (MORMYROUS KANNUME FORSSKAL, 1775) COLLECTED FROM RIVER NILE

Maaly A. Mohammed

Department of Fish Biology and Ecology, Central Lab. for Aquaculture Research, Abbassa, Abo-Hammad, Sharkia, Egypt.

Received 21/ 8/ 2014

Accepted 14/ 10/ 2014

Abstract

This study was carried out to investigate the biology of kanumme, Mormyrous kannume, Nile-inhibiting fish species,
in order to introduce it as a new species for aquaculture. Some biological aspects include, style of living, food and feeding, and reproductive characteristics were evaluated during the period from April 2012 to March 2013. Fish samples were collected from River Nile, Demietta branch at Meet Ghamer region, Dakahleia Governorate. Kannume
shows a scanty abundance in June and July. The length-weight relationship was found to be W = 0.013 L2.866. The total length varied from 13 to 60 cm and the average total body weight varied from 18.6 to 1390.6 g. The mean value of condition factor (K) varied from 0.79 to 0.56 and the relative condition factor (Kn) varied from 0.88 to 0.72. The main food items were chrinomid larvae and dixa. Overall sex ratio was significantly balanced (51% Males and 49% females). The minimum size for maturity in males and females was 28.5 and 22.5cm respectively. The average gonado-somatic index (GSI) of males was quite lower than that of females. The obtained results revealed that females have definite breeding season extended from March to June with a peak in April. Monthly variations in egg diameter were evident with similar variability in GSI. The maximum size of oocytes was recorded in April and May, while the lowest value was recorded in August and September.
Fecundity and variables controlling it were best modeled by stepwise multiple linear regression, which isolated fish size, egg diameter and gonad index to be the best significant factors influencing fecundity and valid for prediction. The absolute fecundity ranged from 140 to 9646 with the growth in length varying from 22 to 54 cm. Fecundity record was highest value in April and May.