I've just rehomed 3 Dendrobates tinctorius. I set the tank for some time before introducing the frogs. All was well with the temp and humidity. I introduced the frogs, they all seemed happy hopping around but now they are all hiding behind this one plant. Is this normal or am I doing something wrong? If the temp drops what other things can I use to increase the temp apart from heat mat. I've heard of a ceramic heat bulb, is this correct????