Corbypete is talking about Belonesox belizanus which is a memeber of the Poecilidae family and is a livebearer.
Females grow larger than males (about 8 inches compared to the males puny 4") which makes breeding difficult as the female is as likely to eat her mate as she is to breed with him!
They preffer a little salt in the water, 2tbls to every 5g is recomended. The fry are born large and are capable of eating newborn gupies straight after birth, they are also highly canabalistic and unless graded by size you will soon be left with just a few very fat individuals.