I would also add that even if you do get the pod population going, the amount that a 20 gal
tank could eventually support would not be nearly enough for the needs of a dragonet. They will in fact need a much larger tank 100+ gal
with a large established population of pods
to actually have a decent chance of survival.
It should also be pointed out that any wrasse is a food competitor for the same pods
and will quite quickly decimate the food supply as fast as it grows.
Wrasses in general are not very recommended for smaller tanks unless of the Cirrhilabrus sp.
or Paracheilinus sp.
families. The latter will usually remain smaller and can be great additions to smaller tanks. Other larger wrasses will make poor choices and outgrow smaller tanks much quicker, not to mention getting very mean and territorial in smaller environments.
Just a curious note. The Indian wrasse
is one of the "common names" for the dragon wrasse which is not
yellow. Are you sure this is the wrasse in question?