Yes, we just stayed at a hotel in Merida. They had small basins with guppies in them, placed in the reception area and around the rooms. They told me that they had not had a mosquito problem since they put those little fish there.

I will try to do the same thing here at our place, if I can find the guppies in Belize - or be allowed to import them without the ususal 300% duty.

Actually also quite pretty little fish too...