Thanks
Thanks for the replies guys. I also talked to some betta breeders and the seedling heat mat with a thermostat is the way to go (as suggested earlier). I'll go with a bigger jar as well. The reason for the jars instead of a small aquarium is because I want to house multiple bettas; don't want to divide a bigger tank because of the danger of transmitting disease from one fish to another.
Thanks for the replies guys. I also talked to some betta breeders and the seedling heat mat with a thermostat is the way to go (as suggested earlier). I'll go with a bigger jar as well. The reason for the jars instead of a small aquarium is because I want to house multiple bettas; don't want to divide a bigger tank because of the danger of transmitting disease from one fish to another.