In July 1997 I lowered the water level in the tank to 18cm and allowed the pH to drop well below 5 and the organic content of the water (especially nitrates) to rise considerably. This was a deliberate attempt to simulate dry season conditions when the flooded river basins of the Amazon shrink to shallow pools. To my surprise, on 13th July the caecilians began to mate. The smaller males entwined themselves around the two much larger females. With their lower bodies entwined and positioned vent to vent, the males inseminated the females (the sexual organ - phallodeum - was large and obvious). This process often lasted for several hours, with initial frenzied activity subsiding into stillness so profound that on more than one occasion I believed that both animals had drowned. Periodic mating continued until 18th July 1997.
After mating had clearly finished, I returned the water conditions to their original state (pH 5/6, dH 3 and 40cm deep). After that things went on as they had before and it was many months before I realized that one of the females was indeed pregnant. This was the largest of the females approximately 55cm long (22 inches). Her girth gradually increased, over the months the diameter of her body reaching more than 6cm at its greatest. The birth finally took place on the night of 10/11th June 1998, 10 months and 3 weeks after mating had ceased. Unfortunately, the births took place during the hours of darkness so I didn't observe the process. Six young were born. One was unfortunately stillborn but the rest are alive at the time of writing (March 2004). The young varied from 10cm-15cm in length and approximately 5mm in diameter. Some still retained external gills which were lost within hours. The young were weak and feeble initially and I immediately dropped the water level to help them get to the surface to breath. The mother did appear to push some of the youngsters towards the surface on occasion although this may nave been coincidental rather than a deliberate act. The young began to feed after a few days, initially on frozen bloodworm and later on finely-chopped adult food. They quickly gained strength and were able to swim rapidly within a week but grew very slowly. At 2 years old, most of the five young had not quite reached 30cm in length and had a body diameter of about 1cm. Currently (March 2004), aged more than 5 years, they are about 45cm in length with a body diameter of 1.5-2.5cm.
All but one of the original adults gradually died between 1998 and 2000. The surviving adult remains active and healthy. I had originally supposed that this was a small male but, in the intervening years, it has matured into a large 60 cm long) female much larger than any of the younger animals. I have had this animal for 9 years now and, judging by the growth rate of the others, it was at least two years old when I obtained it. The 5 year old young have only now achieved the size and maturity exhibited by the original animals when they bred. This implies that Typhlonectes natans is a long lived species which reaches maturity at a fairly advanced age.