Let’s start off by saying that not all fungi and bacteria are harmful; actually, most of them are harmless or even beneficial. Fungi are essential for decomposition, which helps to clean your tank, and they have a symbiotic relationship with plants. Mushrooms don’t seem to cause any detrimental effects in animals in my terrariums. Live plants and beneficial fungi and bacteria can outcompete the harmful fungi and bacteria. Pathogenic or disease-causing bacteria come from infected animals and plants or an unhygienic enclosure. You can avoid infestations of harmful bacteria by buying from reputable breeders. Also, remember the basic importance of quarantining your animals for 3-4 months, regular maintenance of your tank, and buying plants from reputable growers. If you purchase plants, wash the leaves with antibacterial soap, remove any insects, and replace the soil with your own that contains no pesticides/insecticides before you include them in a frog’s terrarium.