What dutchie is saying is if you see fishes that you like, research on where they're from first. If you got a name, you can find out where they're from. If you have soft water, you will try to find species that live in areas with soft water (most Asian and South American species).
Think with logic and rationality more than emotion. Act with moderation and consideration. Contemplate ideals and realistic goals and weigh out possibilities and options. Temper not with personal delusions or false hope but learn to accept and move on.