marine fish are truly amazing unfortunately i do not have them or dont know much about them all i know is that you MUST have salty water, you can but the conditioner from a fish shop or just get water from the beach...i think, but im not sure so i wouldnt try that "get water from beach" idea until you've made sure it is alright i also know they are not cheap. here are some pics of some marine fish, as you can see, they are much more colourful than "normal" fish
