You definately need to use the antibiotic! In addition, you should use AcidophiLiz to help keep the good bacteria, that is normally in their digestive tracts, from being wiped out. This will help with appetite.
I would start using the Parazap after the round of antibiotics is completed; it works best as a preventative.
***The absolute key in treating the coccidia is CLEANILINESS! Disinfect his tank & everything in it. You may want to use 2 plastic tub setups for him until it clears; one for him to be in while the other is being disinfected. Switch between them at least daily. You should only use paper towel substrate & paper plates to put his food on. After handling him or anything with which he's been in contact, wash your hands & change clothing so you're not re-contaminating disinfected items.
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God Bless, Beardie Dreams, & Peace!
Pogoniacs