Black Frog Variant

Hi I just loved the Minecraft Live and wanted to add something for the frogs. So you said when a tadpole is place in a hot and cold environment it changes color. I love this idea but want to add one of my own. So maybe when you put a tadpole in a dark area, like where axolotl's spawn, it would grow into a black frog. I would be cool to have 4 unique frogs types. Also maybe it can have night vision as one of an effect you were working on.