Sera pH test for approx. 80 measurements in fresh or marine water. Tap water usually has a pH between 7.5 and 8.5. Most fish kept in freshwater aquariums originate from neutral or slightly acidic water (pH between 6 and 7). Lake Malawi and Lake Tanganyika cichlids prefer slightly alkaline pH values (7.5 - 8.5). The optimal pH for saltwater aquariums is in the range from 8.2 - 8.4. Do you have questions about this article ?