Egg-laying is quite interesting to observe, when Madam gets out of the water (this costs her a lot of effort) and climbs from 10 to 20 cm (in aquarium) in order to lay her eggs. This operation lasts between 30 minutes and 3 hours and occurs generally by night (probably to avoid predators).
An interesting detail is that the eggs of Pomacea Bridgesii are pink, the ones of Pomacea Canaliculata are red and those of Marisa Nerita (Marisa cornuarietis - South America) are layed in transparent jello-like packs (a little like frog eggs) below water; the embryos are clearly visible.
The eggs, as shown on the picture, are grouped in packs. I may be wrong but consider between 100 and 200 eggs per clutch seems correct. Ten days later, the young snails start to eat the envelope that surounds them and fall into the water - exact replica of the adults ... 1 mm big. Do not forget that each snail must be takent into in the aquarium population, like the fishes.
Copyright © 1999 D.J.Riebesell
As soon as the eggs have proven to be viable and that some 100 to 200 mini snails are wandering about in the aquarium, a serious hygiene problem occurs(most of all if it is also populated with fishes). I have chosen to park them by size in a specific aquarium containing only 60 litres of water. This system has the advantage to offer a simple means to watch the snails and ease maintenance; water still has to be changed regularly, as for any aquarium.
The specimens above don't have more then 5 mm.