Some of these links include beginner guides to general freshwater, and/or general marine saltwater aquarium photography. There are also forums related to cameras and aquariums, but there are also a several links with more specialized tutorials, for example about:

Marine aquarium fish photography, coral photography, shrimp photography, DSLR aquarium photography, mobile phone aquarium photography, koi photography, aquascaping competition photography, aquarium videography and digital editing of aquarium photos and videos.