i would say that its best to keep your vermiculture separate from your froggy friend. They night crawlers need food and this food is decomposed which will release gases into the atmosphere. Also your worms will not like the acidity of your frogs urine. the worms also need to have certain temperature and humidity conditions depending on the species. some worms like colder soil and some like warmer. also, it is best to keep your worms in shredded newspaper. Ill have to try coco fiber for them. im starting my own vermiculture soon with nightcrawlers, but i will be keeping them in a rubbermaid mixed with newspaper and coco fiber. hope this helps.