They are very similar to Mozzies, but you can tell them by the  distinct stripes on the tail fin, (and sometimes the colour of the eyes) and the smaller mouth without the thick lips.
They have a very thick spine in their Anal fin also which is thicker than those of the mozzies.

In most dams they are caught very much the same as Mozzies, by dragging along the bottom, especially during the breeding season, when they are very aggressive and have been known to take small lures (such as Rapala Mini Fatraps and plastic jigs) going through their nests.

In Kariba a ledger fished near shallow weeds used to work well, but those fish are forever changing their minds as to what they will eat and how.
They generally seem to prefer the pellets and doughs, to worms, but one never knows if they want floaters or sinkers.
Again watch for them as they sometimes move around and cruise, so the bites can come in patches with quiet spells in between.
Some "Spots" seem to continously produce thousands of fish, whilst other appear to be there for a day or two and then they are gone.
The larger ones (When they are not breeding) also move out to the trees in Kariba, and divers have reported some large fish just "hanging" around the trees in the deeper water, and are often around with the Mozzies.

In the local dams, watch for the bank anglers wading around in the water and catching them quite quickly. They are finding the nests with their feet, and then placing some algae (on a hook of course) into the nest with their toes. They then set the float so it is standing up, and will bob up to the surface as soon as the fish pulls the line out of the mud, and of course they then strike.
They catch them very quickly and often two around a nest.
If you fancy your chances with the biharzia and the croc's by all means give it a go.