This highly specialized species can reach a length of up to 35 cm. In the literature, the maximum length is often specified as 26 cm, but the salamanders in Turtle Island easily exceed 30 cm in length. As compared to terrestrial salamanders, A. dumerilii is perfectly adapted to aquatic life, with the heavily filamented external gills, streamlined-body form and caudal fins along the tail. The massive head is flattened, enabling the salamander to be an extremely efficient fish hunter. The basic color of the salamander is gray-brown, but they can also have a reddish coloration with strikingly violet external gills. Depending on water temperature, oxygen content and water chemistry, external gills can differ in size and branching. The foot pads and toes of wild caught specimens are chocolate brown. For the animals bred at the Pátzcuaro Basilica, after many generations their dark brown toes have disappeared. The top of their head and body is covered with glands that secrete a milky substance with an unpleasant odor and bitter taste. This liquid is thought to function as a defense mechanism against predators.

Eggs are laid in the winter months when the water temperature of Lake Pátzcuaro cools down to 9 ° C.  Up to 1500 eggs are laid in water plants or glued onto stones. The eggs are left to fate by the parent animals immediately after spawning.

With the very broad, flattened head and lightening quick reflexes, the Pátzcuaro Salamander is able to suck big, living food into its mouth. In the wild, their main food source seems to be the dwarf crayfish (Cambarellus patzcuarensis), which in the pet trade is commonly sold in its orange color morph. Insect larvae and worms are also eagerly consumed. In captivity, A. dumerilii proves to be a voracious feeder. Upon entering a room with an aquarium of A. dumerilii, the hungry animals will stand and beg or relentlessly swim up and down from the surface.

Due to its very limited occurrence in only one Mexican highland lake, which has not been designated as a protected area, A. dumerilii is considered one of the most endangered salamander species . This species was exploited for decades by fishermen for food and medicine for respiratory diseases. It is reported that 19 tons were harvested in 1987, 12.5 tons in 1988, 1.7 tons in 1989, and only 2 tons in 1991. Since 1991, fishermen have not been able to locate them, thus their number is virtually no longer detectable. The fishermen we interviewed have not caught a single salamander in recent years! Due to the lack of modern sewage treatment plants in Pátzcuaro, a city with more than 50,000 inhabitants, the lake is heavily polluted by sewage. The increasing eutrophication causes an annual algae bloom. Additionally, predators, such as the invasive Tilapia sp., have been introduced into the lake and are proliferating.

The salamander’s habitat in Lake Pátzcuaro comprises less than 10 km². The International Union for Conservation of Nature (IUCN) lists Ambystoma dumerilii as ” Critically Endangered.” This species is also listed in the Convention on International Trade in Endangered Species of Wild Flora and Fauna (CITES), Appendix II, as one of the top 5 most endangered salamanders in the world!

For many generations, they have been bred by nuns at the Basilica in Pátzcuaro for the production of cough syrup. In the main entrance hall of the Basilica, there is a large painting depicting their reproduction cycle in the lake, their husbandry and the production of medicine.

Currently, Turtle Island is breeding two unrelated breeding lines and will be able to distribute offspring to collaborating institutions very soon. With this conservation breeding, we hope to contribute to the continued existence of this remarkable and unique salamander.  Our goal is to produce as many healthy salamanders as possible and re-introduce them into Lake Pátzcuaro’s natural habitat after the contamination and invasive species issues have been resolved.