Soft water is generally a good thing when you're keeping fish, because it's a lot easier to make water hard than to make it soft. Tetras, rasboras, danios, barbs, corydoras, loricariid catfish, apistogrammas and other central and south American cichlids (including angelfish and discus), gouramis and most other anabantoids, and most of the dwar rainbows are softwater fish. They will not thrive, and will certainly not breed, if the water is hard. Poeciliid livebearers (guppies, mollies, platys and swordtails, plus the rarer ones like goodeids and limias) are hardwater fish. So are goldfish and the larger Australian rainbowfish, and some of the New Guineans. Many oddball species are hardwater fish, as are gobies, gudgeons, and any fish that can be kept in brackish or freshwater. Most hardwater fish are okay with being kept in moderately soft water, but not extremely soft water. Rift Lake cichlids are the exception; they require extremely hard water that would not be considered for a drinking water supply because it usually has a pH of about 9 and hardness of about 350ppm. Conditioner (mineral salts) must be added to their aquarium to keep them healthy.
Generally, soft to medium water is ideal for keeping a tropical community tank, because most of the small, pretty, schooling species, the 'features' such as gouramis and apistos, and the catfish we like to keep in such tanks prefer soft water. If you do want to keep hardwater fish, it's very easy to adjust the water in their aquarium by adding Rift Lake conditioner at half dosage. Fish that absolutely won't thrive in a softwater aquarium include mollies (particularly sailfins), the rarer wild swordtails, and osme of the more expensive Australian rainbowfish notably Melanotaenia fluviatilis. Invertebrates with a hard shell such as snails and freshwater mussels may not thrive in extremely soft water because they need some minerals to maintain their shells in good condition.
So basically having soft water is a good thing for you, because virtually all of the stock in your signature except the limias and snails (which can more than cope) are softwater species.
