Allowing turtles and newts to live together is not ideal for a number of reasons. The first being that the turtle will most likely end up making the newt its dinner. The second being that amphibians are known to produce toxins that are released through their skins, this could be harmful to your turtle. For instance, if you turtle decides to eat your newt its going to result in the death of both pets. Some newts are also cool water dependent and need temperatures not much warmer than 70 degrees while turtles typically require at least 80 degrees.
A few problems that one might run into when trying to house turtles and newts in the same tank are the changes in temperature requirements, differing dietary requirements, and predation. It is quite common for a turtle to bite off a newt’s tail and injure it in doing so.
Newts typically require a water depth of at least 4 inches as they have to have adequate swimming room. If a newt’s water temperature is higher than 70 degrees Fahrenheit the creature becomes sluggish and inactive. Turtle’s on the other hand require a 55 gallon tank at minimum with at least 40% land and 60% water. Heaters and UV lights are mandatory, and these are not ideal for newts. Turtles also require a basking spot that is 5-10 degrees hotter than the main temperature of the tank.