Hi Roger,

This is covered in the links in the previous post so make sure you go over them a few times.

Temperatures of 65-75 degrees F are fine..but as measured in the Viv. Temps above 77 degrees F should be avoided with mantella (see links). There are some differences with some species, but these general guidelines will work for all of them.

If your Viv stays in this range in the room then it is OK to just use the ambient room heat.
The only caveat is that your lighting will create heat (some more than others) so you must check to make sure that the temps in the viv stay within the range when the lights are ON as well as OFF.

Many opt for keeping their Mantellas in a ground floor or basement where it tends to be on the cooler side and the lights will warm the viv up during the day. The lights will help to generate a variation within the temperature range as naturally occurs.

Others reverse their day/night schedule if the daytime temps are too warm to have the lights on then and instead have them on at night but only if the nighttime temps are cooler in the room.

Adequate ventilation (in at the bottom of the viv and out the top of the viv) similar to the Exo-Terra vivs, etc. will help to cool the viv in a cooler room when the lights are on. In an emergency (unexpected hot day, air conditioning breaks) ice packs could be placed on top of the viv as cold air sinks.

So the best preemptive advice is for you to plan to set up your viv with a thermometer inside so you can see what the actual range is for you before you put them in.....and adjust/modifiy from there. Either obtain the frogs after this and/or keep them in a quarantine setup in a temperature controlled place.

Quarantine in a smaller container is a good idea with new frogs as you can make sure that they are eating and doing well before they are put in the larger viv where they may hide / be difficult to find.

James