Originally Posted by Joderson
Ohh i see! I wont risk it then, ill pick fish or shrimps! One more question, do shrimps fight or can you have all different types and colours in the same tank?
Among the commonly available dwarf shrimp in the hobby, no, they will not fight, they are all peaceful with each other. However, that doesn't mean you should just start mixing a bunch of different kinds of them up randomly. There are 2 reasons you don't want to do that.
Reason #1 is that many of the popular ones are just different color variants of the same species, or else are very, very, very closely related species. This means they can interbreed, and typically when they interbreed, the babies lose the special colors and are simply the "wild" color (usually a drab brown). So if you were to mix species that can interbreed, then your tank that has two wonderfully colored kinds of shrimp now, will be a tank full of nothing but dull brown shrimp a year or two down the road. You probably don't want that.
Reason #2 is that the various dwarf shrimp species have very different preferences for water conditions. Some of them prefer softer, acidic water; others prefer harder, alkaline water. So it's best to first figure out what kind of water you have and then be sure to buy shrimps that are going to do well in your particular setup.
So it is possible to mix a couple of different species together, but you really need to know what you are doing first. (Which, when you think about it, is no different from mixing different species of fish in a community tank. Some combinations work, some don't--so you need to do your research in advance before you go out and start buying stuff.)
Hope that helps. If you want, you can read a lot more about dwarf shrimps in the articles, species profiles, & forums at Arizona Inverts