Marine aquarium fish species are much more difficult to deal with in the aquarium than freshwater varieties. Many species will be completely incompatible and, necessitate the careful selection of species when choosing which fish to include.

Species suitable for beginners :-

• The damselfish,
• The clownfish (also know as the anemonefish).

Species needing experienced care and large tanks:-

• dragonets,
• lionfish.

Species needing expert care and best avoided are:-

• batfishes,
• sharks,
• rays,
• seahorses.

When choosing fish species, their compatibility with other tank occupants such as mollusks, arthropods, plants, and most importantly, corals must be considered.

The Octopus makes an excellent pet, but should be left in a dedicated tank without any fish. They must also be prevented from climbing out of the aquarium, since they are very strong and can survive a remarkably long time outside the water.