Different fish require different water chemistries. One of the factors that affects the type of water a fish needs is water hardness. Hardness means how much concentration of magnesium and calcium is in the water. Soft water has a hardness of between a 0 and 9 degrees of general hardness. Some fish are compatible with any hardness, but others have specific hardness that they need in order to be healthy. Before buying any fish for your tank, do some research as to the water hardness in your area. Here are some of the fish that do best in soft water.
Tinfoil Barbs prefer soft water. They are a large fish, and can grow up to thirteen inches long in captivity. If you have a large tank, this can be a great addition. They have a shiny silver and gold color, and the adults develop red tints in their fins. This is a great fish for a large community tank.
Many of the tetras do best in soft water. Bleeding hearts are one of the favorite varieties. These unique fish got their name because of a distinguishing bright red spot of color on its side. This spot is often in the shape of a heart, and really stands out from their silver-white bodies. They need at least fifteen gallons of space, and as they become comfortable in their environment, their colors will become more pronounced.
Rosy barbs are another fish that prefer soft water. They are hardy when kept in the right environment, and they will breed well in captivity. The males have a rosy color on their underbellies, thus the name. They are a golden color as well. They will jump out of the tank, so make sure you have a tight lid.
Angelfish are perhaps one of the most popular aquarium fish. They will tolerate water that is slightly hard, but they truly thrive in a soft water environment. These graceful fish are not as peaceful as their name implies. They can be fin nippers, so watch them carefully. All in all, however, they do make a great community tank addition.
Plecostomus, or algae eaters as they are commonly referred to, do well in extremely soft water, although they will tolerate hardness as well. If you have a soft water tank, make sure to include a pleco. Keep in mind that they can grow up to two feet long, so makes sure you give them plenty of room.
Silver Dollars are a good addition to a soft water tank. These fish are very peaceful, but need plenty of room because they grow quite large. They also prefer to be kept in schools, so get several if you want to add them to the tank. These fish will not bother other tank mates, but they will eat your live plants, if you have any.
Finally, the red nose or rummy-nose tetra is the perfect addition to a community soft water tank. They can only tolerate water hardness to four degrees, so make sure you know the hardness of your water before buying these fist. Red nose tetras have a unique bright red splash of color on their faces, and in a large school, they create quite a stunning display!