The Biology of Alestes Imberi Peters (Pisces:Characidae) in Lake McIlwaine, Rhodesia

Abstract

The population of Alestes imberi in Lake Mcllwaine increased greatly in late 1974, but the species is of little economic importance in the lake. The breeding season is short and coincides with the main river floods. Females are larger than males and fecundity is extremely high. Like other ,4/M/W species it is a very versatile feeder, and utilizes mainly insect alates from April to November, and chironomid larvae and pupae from December to March. It is able to takeadvantage of periodic insect emergences and to utilize some plant material. Zooplankton and fish are not important food items. Condition factors appear to be related to spawning. Growth rates could only be assessed indirectly but appear to be more rapid in Lake Mcllwaine than in Lake Kariba.