Figure 2 Line drawings of Heterobranchus and malapterurus electricus Nile River catfish. heterobranchus is known to produce a mild electric current, and to an observer above water looking down on it swimming in the water, it is hard to distinguish from its more powerful cousin, the electric catfish malapterurus electricus [Figure 2]. The electric catfish can grow up to 120 cm in length and weigh over 20 kg and, when attacked, will discharge between 100-450 volts. The electric catfish is nocturnal with a voracious appetite, being most active in the feeding 4 to 5 hours after sunset. These features would have been highly significant in Egyptian religious thought — i.e. the passage through the hours of darkness of Osiris who had his phallus eaten by a fish, and even allegorically in the 'Tale of the Two Brothers' where the young brother castrates himself and throws his member to the catfish in the river.