We conclude that pond depth is an important factor in FZT transmission
because it is associated with promoting snail population density.
Whether it is depth per se that promotes snail density or whether
pond depth is associated with some aquaculture practices that promote
snail population needs to be studied in further detail. The importance of
cercariae entering ponds from surrounding habitats needs to be
assessed in relation to source of water for replenishment (canal or
ground water). Hence it is premature to provide specific guidelines to
farmers concerning pond depth. Furthermore, additional studies
would be required to assess whether the same relationship exists in
other systems as well (other fish species and grow-out ponds). In
pond preparation, therefore, emphasis should be placed on pond preparation methods
to minimize snail population density prior to the stocking
of fry but also on habitats surrounding ponds as transmission may
occur through immigration of cercariae produced outside ponds.
Experimental studies on optimum stocking density of fish fry are
recommended.