[Raven]

Ελα Lucy, το βρηκα ! θυμομουν οτι το ειχα διαβασει καπου. Βασικα λεει οτι ο συνδυασμος υψηλης θερμοκρασιας και αφθονου φαγητου κανει τα apple να καταναλωνουν ολη την ενεργεια τους στην αναπαραγωγη και τοτε εμφανιζονται παραμορφωσεις στο κελυφος τους.
Διαβασε εδω που λεει shell detoriation:
http://www.applesnail.net/

The most common cause for shell deformation is a temporary arrest in the shell growth. Due to circumstances (lack of food, lower temperatures) an apple snail can stop growing. This doesn't always mean that the snail is in bad condition or that one should change the environmental conditions. Once the snail reaches a certain size, depending on species and circumstances, it starts using its energy for reproduction efforts instead of growth.
Problems regarding shell growth often start when the temperature suddenly increases in combination with an abundance of food or when the water quality changes (after a large water change). The snail then switches back to the growth stadium and stops with the reproduction efforts. This should not necessarily be a problem, but when the growth line of the mantle edge (were new shell material is made) is damaged the situation changes. Damage in the growth line is often induced by the mating behaviour, when the snails mount each other and the borders of their shell clash. Once the shell grows again, the damaged parts stay behind in growth and an irregular shell border arises. In many occasions, the snail manages to overcome this problem (figure 1), but sometimes the damage can be lethal (figure 2). Besides growth problems due to a damage at the shell-forming tissue near the shell opening, some apple snail species can grow a large, expanding aperture when they reach adulthood, giving them a somewhat trumpet-like shell opening. Especially the male snails develop this appearance, probably as a result of their space occupying penial complex. Such growth should of course not be considered abnormal. To prevent shell grow problems; it's best to avoid sudden changes in the water/food conditions. Always try to keep these factors as constant as possible.
Once a growth problem occurs, it can be quite hard to help the snail. Probably the best thing to do is to slow the growth of the snail down by reducing the amount of food somewhat (don't starve the snail) and by lowering the temperature with a few degree. Once you see that the snail is able to solve the problem, you can choose to elevate the food supply and increase the temperature or you can choose to keep the current conditions. The latter option is attractive if the conditions are still within the optimal way to keep the snails healthy and when your snails have matured enough, so further growth is not desired.