I use supplementary lighting in my viv since it doesn't gets very little natural light. The current setup is an Arcadia 24" T8 "Natural sun" tube which gives out 2% UVb and 10% UVa, plus a small heatmat , together producing a temp of 20-23ºC.
I have noticed that some of the toads lose their vivid colour under this lighting - turning dark brown/black. Removing them to an unlit tank restores the colour within an hour. Putting them back into the viv darkens them within the hour.
I realise that colour variation occurs to some extent naturally as a reaction to surroundings and whilst shedding and perhaps when stressed but health , feeding, temp and humidity are all OK. The substate (moss) is light in colour so I'm sure it's a lighting issue.
Most of the books say that artificial lighting isn't required for FBT's but I wonder about this for a diurnal species that is said to bask. Surely an amount of UVa/b is required, but at what level?
I have tried to reduce the light output by placing a sheet of white paper between the tube and wire mesh lid, the light output is reduced by approx. 50% but the toads are still quite a lot darker than I'd like.
Any suggestions?

Barry

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