GUERRERO: Our systems are as yet experimental but the production per unit area
could probably be improved by using raceways with a flow-through system.
HEPHER: The second bottleneck which I can envisage is obtaining sufficient numbers of
fry at exactly the right age for sex-reversal treatment.
GUERRERO: Using our net enclosure (hapa) system, we can produce 10,000 fry/
500 m2/day.
MORIARTY: Has anyone tried treating with hormones in the tank water? I believe that
aquarists have done this with other species.
GUERRERO: Some people have tried this with tilapias but it has not been effective. Of
course hormone injections are effectivemore so than food incorporation but this is not
practical for sex-reversing fry.
MORIARTY: What about a large quantity of hormone in the water?
GUERRERO: The hormones are not water soluble.
CHERVINSKI: I think I am right in saying that S. aureus has never been sex-reversed by
hormone treatments.
GUERRERO: It has been done successfully for S. niloticus, aureus and nhossambicus.PHILIPPART: Regarding the use of fl6w-through systems, we succeeded last year in
producing sex-reversed S. niloticus in such systems. We had to regulate food input very
carefully. We treated the fish for 29 to 30 days.